Enterprise COBOL ConceptsDr. David Woolbrightwoolbright_david@columbusstate.edu2013

Why Cobol?Billions of lines of existing code with more added each yearDesigned for business Great compilersRuns fastRelatively simple to learnThe language keeps evolving

Enterprise Cobol for z\OS

IBM COBOL: http://www-01.ibm.com/software/awdtools/cobol/zos/

IBM COBOL Documentation:

http://www-01.ibm.com/software/awdtools/cobol/zos/library/

Languagage Referencehttp://publibfp.boulder.ibm.com/epubs/pdf/igy3lr50.pdf

Programming Guidehttp://publibfp.boulder.ibm.com/epubs/pdf/igy3pg50.pdf

Program OrganizationProgram Organized like a book Division Identification, Environment, Data, ProcedureSectionParagraphSentenceClausePhraseWord

Grammatical HierarchyThe grammatical hierarchy follows this form: Identification division Paragraphs Entries Clauses Environment division Sections Paragraphs Entries Clauses Phrases Data division Sections Entries Clauses Phrases Procedure division Sections Paragraphs Sentences Statements Phrases

Coding Rules

Cols 1-6 left blank. Compiler fills in with sequence numbersCol 7 Usually blank,* means comment line, - is continuation, D for debugging linesCols 8-11 A margin or Area ACols 12-72 B margin or Area BCols 73-80 unused1 2 3 4 5 6|7| 8 9 10 11|12 13 71 71 | Seq Nos | | Area A | Area B |

Continuation of StatementsStatements can be continued on the next line in Area B

Continuation of LiteralsContinue the constant through column 71Put a - in column 7Continue constant with a OR Continue constant in area B

Things That Go in Area AArea A items:Division headers Section headers Paragraph headers or paragraph names Level indicators or level-numbers (01 and 77) DECLARATIVES and END DECLARATIVES End program, end class, and end method markers

Things That Go in Area BArea B items:Entries, sentences, statements, and clauses Continuation lines

Things That Go in A or BArea A or BLevel-numbers Comment lines Compiler-directing statements Debugging lines Pseudo-text

Structure of a Program

IDENTIFICATION DIVISIONIDENTIFICATION DIVISION. PROGRAM-ID. HELLO. AUTHOR. JOE SMITH. INSTALLATION. TSYS. DATE-WRITTEN. 12/03/2011. DATE-COMPILED. 12/03/2011.

Only PROGRAM-ID is requiredSome interesting parms can be coded on the PROGRAM-ID

ENVIRONMENT DIVISIONThis division connects external DD file names with internal file names.

ENVIRONMENT DIVISION.INPUT-OUTPUT SECTION.FILE-CONTROL. SELECT MSTRFILE ASSIGN TO MSTRFILE SELECT CUSTOMER-FILE ASSIGN TO CUSTMAST ORGANIZATION IS INDEXED ACCESS MODE IS RANDOM RECORD KEY IS COSTOMER-KEY FILE STATUS IS CUSTOMER-FILE-STATUS.

Internal File NameExternal DD File Name

DATA DIVISIONUsed to create variables and constant fieldsOnly three data types numeric PIC 99999.alphanumeric (text/string) PIC XXX.alphabetic PIC AAA.Level numbers indicate subordination of fields. Use levels 01-49Alphabetic is seldom used

Level NumbersGroup item a subdivided fieldElementary item a non-subdivided field01 Group or independent itemHigher numbers indicate subordinate fields

Level Numbers66, 77, 88 have special significance66 Used to rename (no longer used)77 An independent item (choose 01)88 Condition name

Level Numbers01 XXX. 05 YYY. 10 AAA PIC X. 10 BBB PIC X. 05 ZZZ PIC X(20).

77 AAA PIC 999V99.

Condition Names01 TRAN-CODE PIC X. 88 GOOD VALUE G. 88 BAD VALUE B. 88 INDIFFERENT VALUE I.SET GOOD TO TRUEIF (GOOD)

Equivalent to MOVE G TO TRAN-CODEEquivalent to IF TRAN-CODE = G

Level 88

Condition Names

Picture ClausesPicture clause values usually use 9, X, V, S, A9 a decimal digitX any alphanumeric characterV an implied decimal pointS a signA A-Z, and blank

Picture ClausesPIC 9(6) PIC 9(6)V99 PIC 999999V99 PICTURE X(10) PIC XXXXXXXXXX PIC S9(4)V9(4)PIC S9999V9999 PIC 9(18)

Numeric Edited FieldsXXXBXXBXXXX99/99/99ZZ,ZZZ.99DB***,***.99----.99$$$9.9999999.99

USAGE ClauseSpecifies the format in which data is stored in memoryNormally, the phrase USAGE IS is omitted

01 COST USAGE IS PACKED-DECIMAL PIC S9(5). 01 COST PACKED-DECIMAL PIC S9(5).

01 FIRST-NAME USAGE IS DISPLAY PIC X(20). 01 FIRST-NAME PIC X(20).

DATA DIVISIONWe define data used in input-output operations.

FILE SECTION.FD CUSTOMER-FILE.01 CUSTOMER-MASTER. 05 CUST-NUM PIC 9(2). 05 CUST-FNAME PIC X(20). 05 CUST-LNAME PIC X(20).FD SALES-REPORT.01 REPORT-AREA PIC X(132).

Data FormatsOlder terms: Modern terms:COMPUTATIONAL BINARYCOMP BINARYCOMP-1 FLOATING POINTCOMP-2 FLOATING POINTCOMP-3 PACKED-DECIMALCOMP-4 BINARYCOMP-5 BINARY (NATIVE)05 XDATA PIC S9(5) PACKED-DECIMAL.05 YDATA PIC S9(4) BINARY.

EBCDICEBCDIC is an IBM format for storing alphanumeric characters A - XC1 J - XD1 B - XC2 K - XD2 S XE2 C - XC3 L - XD3 T XE3 D - XC4 M - XD4 U XE4 E - XC5 N - XD5 V XE5 F - XC6 O - XD6 W XE6 G - XC7 P - XD7 X XE7 H - XC8 Q - XD8 Y XE8 I - XC9 R - XD9 Z XE9

EBCDICEBCDIC is an IBM format for storing alphanumeric characters 0 - XF0 SPACE X40 1 XF1 . - X4B 2 - XF2 , - X6B 3 XF3 * - X5C 4 - XF4 - - X60 5 XF5 6 - XF6 7 XF7 8 XF8 9 XF9

BINARY DATAStored in 2s Complement format

Leftmost bit is a sign ( 0 +, 1 - )

If the number is positive, interpret it as plain binary 01011 = 8 + 2 + 1 = + 11

If the number is negative, compute the complement Invert. (Change all 1s to 0s and 0s to 1s.) Add 1. The result is the additive complement

BINARY DATA10011 is a negative number. Inverting we have 01100. Adding 1 we have 01100 + 1 = 01101. This is a positive number. 01101 8 + 4 + 1 = 13, so the original number is -13.

BINARY DATADeclaring a data field as BINARY causes the data to be stored in 2s complement format.

01 X-FIELD PIC S9(4) BINARY VALUE -1.X-FIELD will contain 1111111111111111 = XFFFF.Binary data is processed in a register

PACKED-DECIMAL DATADefining a field to be PACKED-DECIMAL or Computational-3 causes the data to be stored internally in a packed decimal format.

There are 2 decimal digits stored in each byte. A sign is stored in the rightmost nibble. (C +, D -)

Y-FIELD PIC S999 VALUE -23 PACKED-DECIMAL. produces a 2 byte field containing X023D

Most business arithmetic occurs in packed decimal.

Packed No-Sign DataPacked no-sign data is a non-native data type that was created to save space on a disk when storing datesIf the digits in a date like 10/23/89 were stored in a packed field, the field would require 4 bytes: 01|02|38|9CBy removing the sign, the date fits in 3 bytes: 10|23|89

Packed No-Sign DataThese type fields require special handling in CobolProgram PKNOSIGN illustrates how a displayable date can be recovered from a packed no-sign field.

ZONED-DECIMAL DATAA numeric field which is described as DISPLAY, or in which the usage clause is omitted, is stored in a zoned decimal format.

In zoned decimal, each digit takes up one byte, and a sign is stored in the zone portion of the rightmost byte of the field.

Z-FIELD PIC S999 VALUE -32 produces a 3 byte field containing XF0F3D2.

ZONED-DECIMAL DATAZ-FIELD PIC S999 VALUE -32. produces a 3 byte field containing XF0F3D2.Z-FIELD PIC S999 VALUE 32. produces a 3 byte field containing XF0F3C2.W-FIELD PIC 999 VALUE 0. MOVE -32 TO W-FIELD produces a 3 byte field containing XF0F3C2.

DATA DIVISIONDefine the data needed for internal processing in the WORKING-STORAGE SECTION. Storage is statically allocated and exists for the life of the run unit.

WORKING-STORAGE SECTION.01 TOTAL-FIELDS. 05 CUST-TOTAL PIC S9(7)V99 VALUE 0. 05 COST-TOTAL PIC S9(7)V99 VALUE 0.01 DATE-AND-TIME. 05 CD-YEAR PIC 9999. 05 CD-MONTH PIC 99.

DATA RELATIONSHIPS BINARYPACKED-DECIMALCHARACTER orALPHANUMERICZONED-DECIMAL

DATA DIVISIONDescribe data that exists in another program, or storage you want to associate with a symbolic name in the LINKAGE SECTION.

LINKAGE SECTION. 01 LK-DATA-AREA 05 NAME PIC X(40). 05 AGE PIC 999.

DATA DIVISIONThe LOCAL-STORAGE SECTION is used to have storage allocated each time a program is entered, and deallocated on return from the program. Used for compatibility with C or Java.

LOCAL-STORAGE SECTION.01 CUST-NO PIC X(3).01 COST PIC 9(5)V99.

Initialization of StorageWORKING-STORAGE for programs is allocated at the start of the run unit.

Any data items with VALUE clauses are initialized to the appropriate value at that time.

Initialization of StorageFor the duration of the run unit, WORKING-STORAGE items persist in their last-used state. Exceptions are:

1) A program with INITIAL specified in the PROGRAM-ID paragraph In this case, WORKING-STORAGE data items are reinitialized each time the program is entered. IDENTIFICATION DIVISION. PROGRAM-ID. MAIN IS INITIAL. ...

Initialization of StorageFor the duration of the run unit, WORKING-STORAGE items persist in their last-used state. Exceptions are:

2) A subprogram that is dynamically called and then canceled In this case, WORKING-STORAGE data items are reinitialized on the first reentry into the program following the CANCEL. MOVE PROG23 TO PROGID CALL PROGID CANCEL PROGID CALL PROGID

Group and Data Items01 Customer-Record. 05 Customer-Name. 10 Last-Name Pic x(17). 10 Filler Pic x. 10 Initials Pic xx. 05 Part-Order. 10 Part-Name Pic x(15). 10 Part-Color Pic x(10).

REDEFINES01 MONTH-NAMES. 05 STRING-1 PIC X(15) VALUE JANFEBMARAPRMAY. 05 MONTH REDEFINES STRING-1 OCCURS 5 TIMES PIC XXX.

MOVE MONTH(3) TO MONTH-OUT

REDEFINES 05 AMOUNT PIC ZZ9.9-. 05 AMOUNTX REDEFINES AMOUNT PIC X(6).

10 XFIELD PIC 9(5). 10 YFIELD REDEFINES XFIELD. 20 A PIC X(3). 20 B PIC X(2).

LiteralsString Literals enclosed in quotes (single or double) MOVE "INVALID" To CUST-NAME

Numeric literals without quotes MOVE 19 TO CUST-AGE

LiteralsHexadecimal literals with X MOVE XAF3B TO CUST-CODE

ConstantsA constant is a data item that has only one value and it can never change Unfortunately, COBOL does not define a construct specifically for constantsMoral: All values are subject to changeData Division. 01 Report-Header pic x(50) value "Company Report". 01 Interest pic 9v9999 value 1.0265.

Figurative ConstantsThere are some figurative constants supplied by the language: ZERO - an appropriate form of 0SPACE - x40HIGH-VALUES - binary 1s LOW-VALUES - binary 0sQUOTE - a single quoteNULL - binary 0s used for pointersALL - Technically not a figurative constant: X PIC X(5) VALUE ALL 3.

Tables (Arrays)

A table is a set of logically consecutive data items that you define in the DATA DIVISION by using the OCCURS clause. 01 TABLE. 05 TABLE-ENTRY OCCURS 10 TIMES. 10 NUM PIC 99. 10 NAME PIC X(30). 10 ITEM PIC X(5) OCCURS 3 TIMES.

Referencing a Table01 TABLE. 05 TABLE-ENTRY OCCURS 10 TIMES. 10 NUM PIC 99. 10 NAME PIC X(30). 10 ITEM PIC X(5) OCCURS 3 TIMES.

COBOL tables are 1-indexed Some valid References with subscripts:

TABLE-ENTRY(SUB) TABLE NUM(SUB) NAME(SUB) ITEM(SUB1,SUB2)

Subscripts vs IndexesSubscripts are defined separately from the table definitions. 01 MYTABLE. 05 ITEM PIC X(3) OCCURS 10 TIMES. 01 I PIC 9(4) BINARY. ... MOVE 1 TO I MOVE ABC TO ITEM(I)

Subscripts are numeric fields choose BINARY fields for efficiency, although packed and zoned fields also work

Subscripts vs Indexes

Subscripts can be easily printed 01 MYTABLE. 05 ITEM PIC X(3) OCCURS 10 TIMES. 01 I PIC 9(4) BINARY. ... MOVE 1 TO I MOVE ABC TO ITEM(I) DISPLAY I

Subscripts vs IndexesSubscripts represent an occurrence number, 1 is the first occurrence, 2 is the second,

01 MYTABLE. 05 ITEM PIC X(3) OCCURS 10 TIMES. 01 I PIC 9(4) BINARY. ... PERFORM VARYING I FROM 1 BY 1 UNTIL I > 10 DISPLAY ITEM(I) END-PERFORM

Subscript Program

Subscripts vs IndexesIndexes are created when a table is defined 01 MYTABLE. 10 LETTERVALS PIC X(10) VALUE 'ABCDEFGHIJ'. 10 LETTER REDEFINES LETTERVALS PIC X(1) OCCURS 10 TIMES INDEXED BY I. Indexes are manipulated with SET statements and automatically altered by PERFORM statements SET I TO 1 MOVE LETTER(I) TO CHAROUT

Subscripts vs Indexes

Indexes are generally more efficient than subscripts

Indexes represent offsets from the beginning of the table SET I TO 1 Causes I to have the binary value 0 internally.

It takes a bit of work to print them

Index Program

Tables with Two Dimensions01 TABLE. 05 TABLE-ENTRY OCCURS 10 TIMES INDEXED BY SUB1. 10 NUM PIC 99. 10 NAME PIC X(30). 10 ITEM PIC X(5) OCCURS 3 TIMES INDEXED BY SUB2.

Valid References with subscripts: TABLE-ENTRY(SUB1) TABLE NUM(SUB1) NAME(SUB1) ITEM(SUB1,SUB2)

Subscripts and IndexesIn a two-dimensional table, the two subscripts correspond to the row and column numbers.

In a three-dimensional table, the three subscripts correspond to the depth, row, and column numbers.

Indexes use address computation to efficiently reference items in a table.

A Testy ProgramThis program displays You Chose Paper. Why?

PROCEDURE DIVISIONThe PROCEDURE DIVISION is where you code the executable statements in your COBOL programDivided into Paragraphs (terminated with periods): 100-MAIN. DISPLAY HELLO PERFORM 200-SUB GOBACK . 200-SUB. DISPLAY WORLD! .

The Evils of Coding PeriodsPeriods have proven troublesome in the procedure division, and a new style of coding has evolved to deal with them

The period is a statement terminator but we want to think of it as a paragraph terminator only

We will code in a period-less style

Only use periods to end a paragraph name

PROCEDURE DIVISIONTo resolve ambiguity caused by not using periods, we will use statement delimiters: END-IF END-PERFORM END-COMPUTE ...

DISPLAY

DISPLAYHandy for debugging and simple report creationDISPLAY X Y ZDISPLAY "A = " AData is written to SYSOUT

MOVE

MOVE STATEMENT Used to copy data from one field to anotherExample - MOVE X-FIELD TO Y-FIELD Z-FIELDData is copied from the sending field to the receiving field

MOVE STATEMENTTo move data from one field to another field, the two fields should be compatible but dont have to be identically pictured

Alphanumeric - PIC X(10)Numeric - PIC 999v99 Numeric-Edited - PIC 999.99-

Compatible moves: -Alphanumeric to Alphanumeric -Numeric to Numeric -Numeric to Numeric edited

MOVE STATEMENTCompatible moves:

-Alphanumeric to Numeric if the sending field is an unsigned integer

-Alphanumeric to Numeric edited if the sending field is an unsigned integer

-Numeric to Alphanumeric if the sending field is an unsigned integer

MOVE STATEMENTCompatible moves:

-Numeric edited fields can be sent to Numeric and Numeric edited fields this causes a de-edit process to occur -Numeric edited fields can be sent to Alphanumeric and Alphanumeric edited fields this causes a de-edit process to occur

MOVE STATEMENTMoving data can cause data conversions to occur. 01 X PIC S9(4) BINARY. 01 Y PIC S9(5) PACKED-DECIMAL.

MOVE X TO Y

MOVE STATEMENTIf the receiving field is larger than the sending field, the receiving field is filled with leading 0s in a numeric move:

01 X PIC S9(3) VALUE 123. 01 Y PIC S9(5) VALUE 0. MOVE X TO Y RESULT: Y = XF0F0F1F2C3

MOVE STATEMENTIf the receiving field is larger than the sending field, the receiving field is filled with trailing spaces in a alphanumeric move.

01 X PIC X(3) VALUE ABC. 01 Y PIC X(5) VALUE SPACES. MOVE X TO Y RESULT: Y = XC1C2C34040

MOVE STATEMENTIf the receiving field is smaller than the sending field, data will be truncated on the left for numeric moves and on the right for alphanumeric moves 01 X PIC S9(5) VALUE 12345. 01 Y PIC S9(3) VALUE 0. 01 A PIC X(5) VALUE ABCDE 01 B PIC X(3) VALUE SPACES. MOVE X TO Y MOVE A TO B RESULT: Y = XF3F4F5 B = XC1C2C3

Use Move for Assignment 01 WORK. 05 A-FIELD PIC X(3). 05 B-FIELD PIC S999V99.

MOVE ABC TO A-FIELD MOVE 123.45 TO B-FIELD MOVE LOW-VALUE TO WORK

Assignment Can Cause Conversions

Consider the following move:

01 A PIC S999V99.01 B PIC ZZ9.99-.01 C PIC S9(5)V9999 PACKED-DECIMAL. MOVE A TO B Zoned to Numeric-edited MOVE A TO C Zoned to Packed-decimal

MOVE CORRESPONDINGMOVE CORRESPONDING identifier-1 TO identifier-2 CORRUsually a bad ideaBoth identifiers must name group items.Elementary items with the same name are moved.01 A-GROUP. 01 B-GROUP. 05 W PIC X(3). 05 W PIC X(3). 05 X PIC X(2). 05 X PIC X(2). 05 Y PIC 999. 05 Y PIC 999. MOVE CORRESPONDING A-GROUP TO B-GROUPW to W, X to X, Y to Y

MOVE CORRESPONDINGSubordinate items must not be identified by the keyword FILLERNo reference modification for either identifierSubordinate items must not include a REDEFINES, RENAMES, OCCURS, INDEX or POINTER description01 A-GROUP. 01 B-GROUP. 05 W PIC X(3). 05 P PIC X(3). 05 X PIC X(2). 05 X PIC X(2). 05 Y PIC 999. 05 W PIC 999. MOVE CORRESPONDING A-GROUP TO B-GROUPW to W, X to X

INITIALIZE

INITIALIZE SPACE is the implied sending item for receiving items of category alphabetic, alphanumeric, alphanumeric-edited, DBCS, national, or national-edited.ZERO is the implied sending item for receiving items of category numeric or numeric-edited.

INITIALIZE01 PRICE-FIELDS. 05 UNIT-PRICE PIC 9(5)V9(2) PACKED-DECIMAL. 05 DISCOUNT PIC V9(2). 05 UNIT-CODE PIC XX. 05 SALES-PRICE PIC S9(4) BINARY. . . . INITIALIZE PRICE-FIELDS

ADD

ADD SemanticsAll identifiers or literals that precede the keyword TO are added together, and this sum is added to and stored in identifier-2. This process is repeated for each successive occurrence of identifier-2 in the left-to-right order in which identifier-2 is specified. ADD X Y Z TO P Q Before X=1, Y=2, Z=3, P=4, Q=6 After X=1, Y=2, Z=3, P=10, Q=12

ADD EXAMPLESADD X TO YADD X Y Z TO PADD X Y TO P QADD 1 TO ZADD X TO Y ROUNDEDADD X TO Y ON SIZE ERROR DISPLAY ADD ERROR END-ADD

ADD GIVING

ADDGIVING SemanticsAll identifiers or literals that precede the keyword TO are added together, and this sum is added to identifier-2 to obtain a temporary sum. (Identifier-2 is unchanged) The the temporary sum is moved to identifier-3. ADD X Y Z TO V GIVING P Before X=1, Y=2, Z=3, V=4, P=6 After X=1, Y=2, Z=3, V=4, P=10

SUBTRACT

SUBTRACTAll identifiers or literals preceding the keyword FROM are added together and their sum is subtracted from and stored immediately in identifier-2. This process is repeated for each successive occurrence of identifier-2, in the left-to-right order in which identifier-2 is specified. SUBTRACT X Y FROM P Q Before: X=1,Y=2, P=3,Q=4 After: X=1,Y=2, P=0,Q=1

SUBTRACT

SUBTRACT SemanticsAll identifiers or literals preceding the keyword FROM are added together and their sum is subtracted from identifier-2 to obtain a temporary value which is moved to identifier-3. SUBTRACT X Y FROM P GIVING Q Before: X=1,Y=2,P=5,Q=6 After: X=1,Y=2,P=5,Q=2

MULTIPLY

MULTIPLY SemanticsIn format 1, the value of identifier-1 or literal-1 is multiplied by the value of identifier-2; the product is then placed in identifier-2. For each successive occurrence of identifier-2, the multiplication takes place in the left-to-right order in which identifier-2 is specified. MULTIPLY X BY P Q Before: X=2,P=4,Q=5 After: X=2,P=8,Q=10

MULTIPLY

MULTIPLYIn format 2, the value of identifier-1 or literal-1 is multiplied by the value of identifier-2 or literal-2. The product is then stored in the data items referenced by identifier-3. Identifier-2 is unchanged. MULTIPLY X BY Y GIVING Z Before: X=2, Y=3, Z=4 After: X=2, Y=3, Z=6

DIVIDE

DIVIDEIn format 1, the value of identifier-1 or literal-1 is divided into the value of identifier-2, and the quotient is then stored in identifier-2. For each successive occurrence of identifier-2, the division takes place in the left-to-right order in which identifier-2 is specified. DIVIDE X INTO Y Z Before: X=3, Y=7, Z=12 After: X=3, Y=2, Z=4

DIVIDE

DIVIDEIn format 2, the value of identifier-1 or literal-1 is divided into the value of identifier-2 or literal-2. The value of the quotient is stored in each data item referenced by identifier-3. DIVIDE X INTO Y GIVING Z Before: X = 2, Y = 13, Z = 1 After: X = 2, Y = 13, Z = 6

DIVIDE

DIVIDEIn format 3, the value of identifier-1 or literal-1 is divided by the value of identifier-2 or literal-2. The value of the quotient is stored in each data item referenced by identifier-3. DIVIDE X BY Y GIVING Z Before: X = 10, Y = 3, Z = 1 After: X = 10, Y = 3, Z = 3

DIVIDE

DIVIDEIn format 4, the value of identifier-1 or literal-1 is divided into identifier-2 or literal-2. The value of the quotient is stored in identifier-3, and the value of the remainder is stored in identifier-4. DIVIDE X INTO Y GIVING Z REMAINDER R Before: X = 2, Y = 9, Z = 8, R = 7 After: X = 2, Y = 9, Z = 4, R = 1

COMPUTE

COMPUTECOMPUTE can be used to initialize a numeric fieldUsually reserved for nontrivial computations. For simple computations choose ADD, SUBTRACT, MULTIPLY or DIVIDE

05 X PIC S9(4)V9 PACKED DECIMAL.

COMPUTE X ROUNDED = (A + B) / 2.3 ON SIZE ERROR DISPLAY X WAS TRUNCATEDEND-COMPUTE

Arithmetic OperatorsParentheses provide precedence. Always parenthesize!((X + Y) * ( Z ** 3))

OperationOperator+Addition-Subtraction*Multiplication/Division**Exponentiation

Locate Mode I/OInput BuffersOutput BuffersYour Program Region

Move Mode I/OInput BuffersOutput BuffersREAD MYFILE INTO MYRECWRITE RECOUT FROM MYREC Region01 MYREC PIC X(80).

QSAM FILE OPERATIONS ENVIRONMENT DIVISION. INPUT-OUTPUT-SECTION. FILE-CONTROL. SELECT MY-INPUT-FILE ASSIGN TO MASTER FILE STATUS IS MAST-STAT. MY-INPUT-FILE Internal file nameMASTER External DD nameMAST-STAT A two byte PIC XX field in which the operating system returns a status code. Consult IBM Language Reference page 315 for status code details.

QSAM FILE OPERATIONS

ENVIRONMENT DIVISION. INPUT-OUTPUT-SECTION. FILE-CONTROL. SELECT MY-INPUT-FILE ASSIGN TO MASTER FILE STATUS IS MAST-STAT.

DATA DIVISION. FILE SECTION. FD MY-INPUT-FILE 01 RECORD-AREA PIC X(80).

QSAMQueued Sequential Access MethodFor input files, records are buffered when the file is OPENedFor output, records are buffered before being writtenRecords are processed from the beginning record sequentially to the end of the fileVery efficient access method for sequential filesSometimes referred to as flat files

QSAM FILE OPERATIONSEvery file must be OPENed before it can be processed.Opening a QSAM Input file queues records for subsequent read operationsOPEN INPUT MY-INPUT-FILEOPEN OUTPUT MY-OUTPUT-FILEFiles should be closed when you have finished processing the recordsCLOSE MY-FILE

OPEN

CLOSE

READ

QSAM Input File OperationsRemember: READ a file, WRITE a record. READ MY-INPUT-FILE AT END MOVE NO TO MORE-RECS END-READThis is a locate-mode read and the most efficient way to read records

File Reading READ MY-INPUT-FILE INTO MY-REC AT END MOVE NO TO MORE-RECS END-READ WRITEThis is a move-mode read and the least efficient way to deliver records

QSAM Output File OperationsWrite a record!WRITE MY-RECORD (locate mode)WRITE MY-RECORD FROM REC-BUFF END-WRITE (move mode)CLOSE MY-OUTPUT-FILECLOSE MY-INPUT-FILE

Sequential File Reading PatternREAD MYFILE AT END MOVE N TO MORE-RECSEND-READPERFORM UNTIL MORE-RECS = N (process a record code) READ MYFILE AT END MOVE N TO MORE-RECS END-READEND-PERFORMPRIMING READCONTINUATION READ

File Status Codes00 normal10 end of file2x invalid key3x permanent i/o error4x logic error9x unsuccessful operation

Exercise #1Create a file of 80 byte recordsEach record has 3 fieldsAFIELD ZONED DECIMAL with 4 DIGITS & 2 DECIMALSBFIELD PACKED DECIMAL with 7 DIGITS & 3 DECIMALSCFIELD - PACKED DECIMAL with 7 DIGITS & 1 DECIMALPrint a report with a column for each field and a column for the computed value : (AFIELD + BFIELD)/ CFIELD Print the result with 2 decimals rounded. Total each column.

FLOW OF CONTROLThere is a theoretical result in Computer Science by two Italian mathematicians, Boehm and Jacopini, that states that only 3 control structures are required to write any program:Sequence - Do this, now do this, now do this, Selection - If something is true do this, else do thatRepetition While something is true, do thisPractice has shown that being able to create procedures is helpful in overcoming complexity, but they arent strictly necessaryOne implication of this result is that GO TO statements arent needed

FLOW OF CONTROL?TFFT

IF

IFThe condition is tested and either the true or false blocks are selected for executionDont use NEXT SENTENCE if you are using END-IF as the delimiter (and you should). Use of NEXT SENTENCE causes execution to continue with the next closest period, which is probably the end of the paragraph.

IF Examples IF X < Y ADD 1 TO X DISPLAY AAA ELSE DISPLAY BBB END-IF

IF X > Y DISPLAY X WAS BIGGER END-IF

NESTED IFsEach ELSE is matched with the nearest preceding IF IF X < Y DISPLAY XXX IF Y < Z DISPLAY ZZZ ELSE DISPLAY AAA END-IFMORAL: Indent properly and terminate all if statements with END-IF

EVALUATE

EVALUATEEVALUATE PLANET-NUMBER WHEN 1 MOVE "Mercury" TO PLANET-NAME WHEN 2 MOVE "Venus " TO PLANET-NAME WHEN 3 MOVE "Earth " TO PLANET-NAME WHEN 4 MOVE "Mars " TO PLANET-NAME WHEN 5 MOVE "Jupiter" TO PLANET-NAME WHEN 6 MOVE "Saturn " TO PLANET-NAME WHEN 7 MOVE "Uranus " TO PLANET-NAME WHEN 8 MOVE "Neptune" TO PLANET-NAME WHEN 9 MOVE "Pluto " TO PLANET-NAME WHEN OTHER MOVE " " TO PLANET-NAMEEND-EVALUATE.

EVALUATEEVALUATE PLANET-NAME WHEN "Mercury" MOVE 1 TO PLANET-NUMBER WHEN "Venus " MOVE 2 TO PLANET-NUMBER WHEN "Earth " MOVE 3 TO PLANET-NUMBER WHEN "Mars " MOVE 4 TO PLANET-NUMBER WHEN "Jupiter" MOVE 5 TO PLANET-NUMBER WHEN "Saturn " MOVE 6 TO PLANET-NUMBER WHEN "Uranus " MOVE 7 TO PLANET-NUMBER WHEN "Neptune" MOVE 8 TO PLANET-NUMBER WHEN "Pluto " MOVE 9 TO PLANET-NUMBER WHEN OTHER MOVE 0 TO PLANET-NUMBER END-EVALUATE.

EVALUATEEVALUATE TRUE WHEN PLANET-NAME = "Mercury" MOVE 1 TO PLANET-NUMBER WHEN PLANET-NAME = "Venus " MOVE 2 TO PLANET-NUMBER WHEN PLANET-NAME = "Earth " MOVE 3 TO PLANET-NUMBER WHEN PLANET-NAME = "Mars " MOVE 4 TO PLANET-NUMBER WHEN PLANET-NAME = "Jupiter" MOVE 5 TO PLANET-NUMBER WHEN PLANET-NAME = "Saturn " MOVE 6 TO PLANET-NUMBER WHEN PLANET-NAME = "Uranus " MOVE 7 TO PLANET-NUMBER WHEN PLANET-NAME = "Neptune" MOVE 8 TO PLANET-NUMBER WHEN PLANET-NAME = "Pluto " MOVE 9 TO PLANET-NUMBER WHEN OTHER MOVE 0 TO PLANET-NUMBER END-EVALUATE.

EVALUATEEVALUATE Qty ALSO TRUE ALSO Member WHEN 1 THRU 5 ALSO VOP < 501 ALSO "Y" MOVE 2 TO Discount WHEN 6 THRU 16 ALSO VOP < 501 ALSO "Y" MOVE 3 TO Discount WHEN 17 THRU 99 ALSO VOP < 501 ALSO "Y" MOVE 5 TO Discount WHEN 1 THRU 5 ALSO VOP < 2001 ALSO "Y" MOVE 7 TO Discount WHEN 6 THRU 16 ALSO VOP < 2001 ALSO "Y" MOVE 12 TO Discount WHEN 17 THRU 99 ALSO VOP < 2001 ALSO "Y" MOVE 18 TO Discount WHEN 1 THRU 5 ALSO VOP > 2000 ALSO "Y" MOVE 10 TO Discount WHEN 6 THRU 16 ALSO VOP > 2000 ALSO "Y" MOVE 23 TO Discount END-EVALUATE

EVALUATEEVALUATE TRUE ALSO Position WHEN L-Arrow ALSO 2 THRU 10 SUBTRACT 1 FROM Position WHEN R-Arrow ALSO 1 THRU 9 ADD 1 TO Position WHEN L-Arrow ALSO 1 MOVE 10 TO Position WHEN R-Arrow ALSO 10 MOVE 1 TO Position WHEN DelKey ALSO ANY PERFORM DeleteChar WHEN Char ALSO 1 THRU 9 PERFORM InsertChar ADD 1 TO Position WHEN Char ALSO 10 PERFORM InsertChar WHEN OTHER PERFORM DisplayErrorMessage END-EVALUATE

PERFORM

PERFORM ParagraphPERFORM paragraph nameExecute all instructions in the paragraphReturn control to the next instruction after the PERFORMPERFORM 100-ROUTINEPERFORM 200-ROUTINEPERFORM 100-ROUTINE100-ROUTINE. 200-ROUTINE. 300-ROUTINE.

PERFORM THRUPERFORM paragraph name THRU paragraph name

PERFORM 100-XXX THUR 100-XXX-EXIT 100-XXX. DISPLAY IN 100-XXX. 100-XXX-EXIT. EXIT.There is an implicit EXIT in every paragraph so why do I need to code it explicitly?

Perform Thru (Let it Die)I view use of PERFORMTHRU as an older, unnecessary style, caused by a compiler problem that existed many years ago. Using PERFORM THRU was a way to address this ancient problem. The problem has been fixed for many years now, yet old habits die hard.

PERFORM WITH TIMES

PERFORM x TIMESMOVE 5 TO COUNTPERFORM COUNT TIMES DISPLAY XXXEND-PERFORM

PERFORM 100-DISPLAY COUNT TIMES

PERFORM UNTIL

PERFORM UNTIL MOVE 0 TO X PERFORM UNTIL X > 10 MOVE X TO X-EDITED DISPLAY X-EDITED ADD 1 TO X END-PERFORMPERFORM X-PARA UNTIL X > 10PERFORM X-PARA WITH TEST AFTER UNTIL X > 10

PERFORM VARYING

Inline PerformPERFORM VARYING X FROM 1 BY 1 UNTIL X > 100 DISPLAY XEND-PERFORM

PRINTS:123100

Inline PERFORMPERFORM VARYING X FROM 5 BY -1 UNTIL X =0 DISPLAY XEND-PERFORM

PRINTS: 543210

Inline PERFORMMOVE 10 TO XPERFORM WITH TEST AFTER UNTIL X = 0 DISPLAY X SUBTRACT 1 FROM XEND-PERFORM

PERFORM PARAGRAPHPERFORM 100-RTN WITH TEST AFTER VARYING X FROM 1 BY 1 UNTIL X = 100100-RTN. .

Inline PERFORMMOVE ZERO TO YPERFORM UNTIL X = 0 READ AT END MOVE 0 TO X ADD X TO Y DISPLAY YEND-PERFORM

Alternate PERFORM PERFORM 100-PARA VARYING I FROM 1 BY 1 UNTIL I > 5 AFTER J FROM 1 BY 1 UNTIL J > 3 END-PERFORM100-PARA. DISPLAY I J .1 11 21 32 12 22 33 13 23 34 1

Table Processing with Subscripts01 TOT PIC S9(8) PACKED DECIMAL.01 SUB1 PIC 99.01 TEMP-REC. 05 TEMP OCCURS 12 TIMES PIC S9(4).MOVE 0 TO TOTPERFORM VARYING SUB1 FROM 1 BY 1 UNTIL SUB1 > 12 ADD TEMP(SUB1) TO TOT ENDPERFORM

Table Processing with Indexes01 TOT PIC S9(8) PACKED DECIMAL.

01 TEMP-REC. 05 TEMP OCCURS 12 TIMES INDEXED BY K PIC S9(4).MOVE 0 TO TOTPERFORM VARYING K FROM 1 BY 1 UNTIL K > 12 ADD TEMP(K) TO TOT END-PERFORM

Manipulating IndexesIndexes cant be manipulated with ordinary arithmetic commands. Instead use SET.SET K TO 3SET K UP BY 1SET K UP BY 2SET K DOWN BY 3

CONTINUE

Used to indicate that no operation is present.

EXITSometimes used to provide an explicit exit from a paragraph or a program.There is an implicit exit at the end of each paragraph100-PARA. DISPLAY X EXIT .

STOPUsually used to permanently halt execution of a programCan be used to temporarily halt execution and require operator intervention

GOBACKFunctions like an EXIT PROGRAM when coded at the end of a called programFunctions like STOP RUN when coded in a main programI prefer coding this in place of STOP RUN

GO TOCauses an unconditional jump in program execution to the procedure that is named.This statement should be used only in very special situations, for instance, to branch to an error routine that terminates the program from a deeply nested area of your program.Overuse (any?) of this statement is unnecessary and leads to spaghetti codeDont even think of using the alternate forms of GO TO !

Exercise #2Create a file of 80 byte recordsEach record has 3 fieldsCUSTLNAME CHARACTER 15CUSTFNAME - CHARACTER 15BALANCE - PACKED DECIMAL 5 BYTES 2 DECSCreate a table of the file data using subscripts.Sort the table with a bubble sort on customer name.Print the sorted table: Last Name First Name Balance

Exercise #3Repeat Exercise #2 using indexes

SEQUENTIAL SEARCH

SEARCHSearch performs a sequential search with an indexRule of thumb: Use SEARCH for tables with 20 items or lessDEPENDING ON field must contain the number of table entries01 RECCOUNT PIC 9(2).01 SALES-TAX. 05 TAB-ENTRIES OCCURS 20 TIMES DEPENDING ON RECCOUNT INDEXED BY K. 10 ZIPCODE PIC 9(5). 10 RATE PIC V999.

SET K TO 1SEARCH TAB-ENTRIES AT END MOVE 0 TO TAX WHEN ZIPIN = ZIPCODE(K) COMPUTE TAX = RATE(K) * AMOUNTEND-SEARCH

Exercise #4Read the file from exercise #3

Store the data in a table

Read the file BCST.SICCC01.PDSLIB(DAT4EXER). Each record has a LAST NAME, FIRST NAME field: Last name columns 1 15 First name columns 16 30Code a Sequential Search statement to find each name in the file. Print each name, Found or Not Found, and the customer balance if found.

SEARCH ALL

SEARCH ALLSEARCH ALL performs a binary search with an indexENTRIES MUST BE IN ORDER BY KEY! No SET necessary (the whole table is searched)RECCOUNT must contain the number of table entries.01 RECCOUNT PIC 999 PACKED-DECIMAL.01 SALES-TAX. 05 TAB-ENTRIES OCCURS 100 TIMES DEPENDING ON RECCOUNT ASCENDING KEY ZIPCODE INDEXED BY K. 10 ZIPCODE PIC 9(5). 10 RATE PIC V999.

SEARCH ALL TAB-ENTRIES AT END MOVE 0 TO TAX WHEN ZIPCODE(K) = ZIPIN COMPUTE TAX = RATE(K) * AMOUNTEND-SEARCH

SEARCH ALL CONSTRAINTSThe condition following WHEN must test for equalityCompound conditions with ANDs not ORsOnly one WHEN clauseVARYING not allowedOCCURS item and its index must appear on the left of the equal signWHEN TEMP(K) = 80

SEARCH ALL ConstraintsTable must indicate ASCENDING or DESCENDING KEY01 TABLE. 05 CUST-REC OCCURS 40 TIMES DEPENDING ON RECCOUNT ASCENDING KEY CUST INDEXED BY K. 10 CUST PIC 9(4). 10 RATE PIC V999.

Exercise #5Read the file from exercise #3

Store the data in a table

Read the file BCST.SICCC01.PDSLIB(DAT4EXER). Each record has a LAST NAME , FIRST NAME fields Last name columns 1 15 First name columns 16 30Code a binary search statement to find each name in the file. Print each name, Found or Not Found, and the customer balance if found.

STRING

STRINGUsed to build string expressions by concatenation (blanks not stored)STRING FNAME DELIMITED BY MNAME DELIMITED BY LNAME DELIMITED BY INTO NAME-OUT

STRINGBlanks storedDELIMITED BY SIZE means include the entire literal or variable contents

STRING FNAME DELIMITED BY DELIMITED BY SIZE MNAME DELIMITED BY DELIMITED BY SIZE LNAME DELIMITED BY DELIMITED BY SIZE INTO NAME-OUT

STRING

UNSTRING

UNSTRINGSeparates a string into several component stringsSending field must be alphanumeric

UNSTRING NAME DELIMITED BY , INTO LNAME FNAME MIEND-UNSTRING

UNSTRINGUNSTRING JCL-DATA DELIMITED BY ALL SPACES OR ALL ',' INTO WS-DATE-REQUESTED WS-DATE1 WS-DATE2 END-UNSTRING

Exercise #6Read the file BCST.SICCC01.PDSLIB(STRINGS)Print the first name, middle initial, and last names in columns

Exercise #7Read the file BCST.SICCC01.PDSLIB(STRINGS1)Print the digits followed by the letters. Use / as the delimiter of the two fields.

CALL

Static and Dynamic CallPrograms A and B that are linked together prior to being loaded are statically linked. If A calls B, the call is staticIf programs A and B are separately compiled and linked, A can call B dynamically: 01 PGMNAME PIC X(8) VALUE B. CALL PGMNAME

Calling Other Programs StaticallyCALL literal program name USING identifier-1, Examples CALL CUST1030 USING X,Y CALL PROG1000

CALLING ANOTHER PROGRAMCALL PROGXXXX USING A,B

IDENTIFICATION DIVISION.PROGRAM-ID. PROGXXXX.LINKAGE SECTION.01 X PIC X(5).01 Y PIC 999V99.PROCEDURE DIVISION USING X,Y. GOBACK .

Static and Dynamic CALLSTwo methods for generating dynamic callsCALL MYPROG USING X,Y,Z (Using an identifier insures a dynamic call.)DYNAM/NODYNAM compiler option determines whether a static or dynamic call occursAt TSYS all calls are dynamic.

Exercise #8Write a main program that, 1) Prints I am in the main program, 2) Calls your subprogram, 3) Prints I am back in the main programWrite a subprogram that prints I am in the subprogram.Compile and link the programs, execute the main program

Exercise #9Write a main program that passes 3 packed decimal numbers to a subprogram and a fourth variable in which to receive a result.Write a subprogram that accepts the 3 integers, computes their sum and returns the answer to the mainHave the main print the result

Exercise #10Write a main program that passes a variable X by reference and Y by contentHave the subprogram add one to both numbersHave the main program print X and Y after returning from the subprogram

NUMERIC Class TestBefore using a suspect field that has a PIC of 9s, use the NUMERIC class test to verify the field before doing arithmetic

IF AMOUNT-IN IS NUMERIC ADD 1 TO AMOUNT-INELSE DISPLAY AMOUNT IS NOT NUMERICEND-IF

Sign TestNumeric data can be tested for positive, negative, and zero values

IF AMOUNT-IN IS POSITIVE ADD 1 TO AMOUNT-INEND-IFIF AMOUNT-IN IS NEGATIVE DISPLAY AMOUNT-INEND-IFIF AMOUNT-IN IS ZERO DISPLAY THE FIELD IS ZEROEND-IF

INSPECT (TALLYING)

INSPECT (TALLYING)INSPECT MYLINE TALLYING ECOUNT FOR ALL E AFTER INITIAL START" BEFORE INITIAL ENDEND-INSPECT INSPECT WORK TALLYING COUNT1 FOR LEADING * COUNT2 FOR CHARACTERSEND-INSPECTINSPECT WORK TALLYING COUNT1 FOR ALL * BEFORE . COUNT2 FOR ALL CHARACTERS AFTER .END-INSPECT

INSPECT (REPLACING)

INSPECT (REPLACING)INSPECT MYDATA REPLACING ALL X" BY Y AFTER INITIAL A" BEFORE INITIAL Z

INSPECT MYDATA REPLACING LEADING " BY +

INSPECT MYDATA REPLACING ALL A" BY + AFTER INITIAL X" INSPECT MYDATA REPLACING FIRST A" BY +" AFTER INITIAL A" BEFORE INITIAL Z

INSPECT MYDATA REPLACING ALL AAAA" BY ZZZZ"

INSPECT (CONVERTING)

INSPECT (CONVERTING)INSPECT TEXTLINE CONVERTING "abcdefghijklmnopqrstuvwxyz" TO "ABCDEFGHIJKLMNOPQRSTUVWXYZ"

INSPECT FIELDA CONVERTING 1234567890 TO ABCDEFGHIJ

REFERENCE MODIFICATIONAllows you to process PIC 9 and PIC X fields as if they were an array of characters.FIELDNAME(start pos : [ length])

05 FIELDA PIC X(7) VALUE ABCDEFG.

FIELDA(1:3) ABCFIELDA(2:2) BCFIELDA(4: ) DEFG

Qualification of NamesCOBOL allows the same variable name to be used to define fields in different records or group items.Duplicate names must be qualified when they are referenced01 XFIELD. 05 YFIELD. 10 ZFIELD PIC X(3).If ZFIELD is a duplicate name it can be qualified in two ways: ZFIELD OF YFIELD ZFIELD OF XFIELD

Intrinsic FunctionsCOBOL does not permit user-defined functions or proceduresIntrinsic (built-in) Functions can be used in your programsThree broad categories of intrinsic functions: date functions, numeric functions and string functions.

Intrinsic FunctionsIntrinsic Function values are replaced in the position where they occur by the function result.

In COBOL, an Intrinsic Function is a temporary data item whose value is determined at the time the function is executed. Functions that return a number value (numeric & integer) are always considered to be signed. A function that returns a number value can be used only in an arithmetic expression or as the source of a MOVE statement.

Intrinsic FunctionsIntrinsic function pattern: FUNCTION FunctionName(Parameters)FunctionName is the name of the function and Parameters is one or more parameters supplied to the function.

COMPUTE NUM = FUNCTION RANDOM(99) MOVE FUNCTION REVERSE(ABCD) TO NAME

Sample Intrinsic FunctionsCHAR(PosInt) AlphanumericReturns the character at ordinal position PosInt of the collating sequence. ORD(Alph) IntegerReturns the ordinal position of character Alph. ORD-MAX({Any}...) IntegerReturns the ordinal position of whichever of the parameters has the highest value. All parameters must be of the same type. The parameter list may be replaced by an array.ORD-MIN({Any}...) IntegerReturns the ordinal position of whichever of the parameters has the lowest value. All parameters must be of the same type.

Intrinsic FunctionsREVERSE(Alph) Alphanumeric Returns a character string with the characters in Alph reversed. LOWER-CASE(Alph) Alphanumeric Returns a character string with the characters in Alph changed to their lower case equivalents. UPPER-CASE(Alph) Alphanumeric Returns a character string with the characters in Alph changed to their upper case equivalents

Date Intrinsic FunctionsCURRENT-DATE - Returns a 21 character string representing the current date and timeDATE-OF-INTEGER(PosInt) - Returns the yyyymmdd (standard date) equivalent of the integer date - PosInt. The integer date is the number of days that have passed since Dec 31st 1600 in the Gregorian Calendar.

Math Intrinsic FunctionsMAX({Any}...)Return type on type of Any. Takes a parameter list and returns the content of whichever parameter contains the maximum value. The returned type depends upon the parameter types as follows; Alphanumeric if parameters are Alphabetic or Alphnumeric. Integer if all are integer. Numeric if all are Numeric. An array may be used instead of the parameter list.

Math Intrinsic FunctionsSQRT(Num) Returns an approximation of the square root of Num.STANDARD-DEVIATION({Num}...) Returns an approximation of the standard deviation of its parameters.And many others

Condition Names01 NO-OF-NEIGHBORS PIC 9. 88 JUST-RIGHT VALUE 2 THRU 3. 88 TOO-FEW VALUE 0 THRU 1. 88 TOO-MANY VALUE 4 THRU 8.01 MARITAL-STATUS PIC X. 88 VALID-STATUS VALUE S M D W.

Variable Length Tables01 TCOUNT PIC S9(3) PACKED-DECIMAL.01 STATE-TABLE. 05 ST-GROUP OCCURS 1 TO 100 TIMES DEPENDING ON TCOUNT ASCENDING KEY IS ZIP INDEXED BY NDX. 10 ZIP PIC X(5). 10 RATE PIC V9999.

Loading a Variable Length TablePERFORM WITH TEST AFTER VARYING NDX FROM 1 BY 1 UNTIL PTABLE-EOF OR NDX = 100 PERFORM FILE-READ IF NOT PTABLE-EOF MOVE ZIP-IN TO ZIP(NDX) MOVE RATE-IN TO RATE(NDX) ELSE SET NDX DOWN BY 1 SET TCOUNT TO NDX END-IFEND-PERFORM

Exercise #11Read the file BCST.SICCC01.PDSLIB(STATES)

Store the data in a variable length table

Read the file BCST.SICCC01.PDSLIB(COBDATA4). Each record has a 2 digit state code and a 5 byte zip code. For each record in this file print a record on a report. The report will have the following format:

GA 31907 GEORGIA - VALID ZIP AND STATE CA 90003 CALIFORNIA - INVALID ZIP ZD 30002 INVALID STATE

Capitalize the state name found in the table. Print message next to each state name separated by a dash.

Use the SEARCH command perform a sequential search of the table for each look up. After the program is working, modify it to perform a binary search with SEARCH ALL

Files with Multiple Record TypesFD TransFile. 01 InsertRec. 02 RECI PIC X. 02 STUDENTIDI PIC 9(7). 02 STUDENTNAME. 03 SURNAME PIC X(8). 03 INITIALS PIC XX. 02 DOB. 03 YOBIRTH PIC 9(4). 03 MOBIRTH PIC 99. 03 DOBIRTH PIC 99. 02 COURSECODE PIC X(4). 02 GENDER PIC X. 01 DELETEREC. 02 RECD PIC X. 02 STUDENTIDD PIC 9(7). 01 UpdateRec. 02 STUDENTIDU PIC 9(7). 02 NEWCOURSECODE PIC X(4).

Multiple O1 File DescriptionsAny number of 01 record descriptions can be coded with the FDOnly one buffer is used no matter how many record descriptions have been codedRecord fields cant be referenced before the file is opened or after it is closedWith multiple record formats, there needs to be a fixed field to indicate the record typeValue clauses are only used for 88 level items

Writing With Carriage Control

Variable Length RecordsThe RECORD IS VARYING IN SIZE clause specifies a file containing variable length records.

Variable Length RecordsThe RECSIZE number in the DEPENDING ON phase must be an elementary unsigned integer data-item declared in the WORKING-STORAGE SECTION.FD TRANFILE RECORD IS VARYING IN SIZE FROM 1 TO 80 CHARACTERS DEPENDING ON RECSIZE.

Variable Length Record ProcessingWhen writing a variable length record, the size of the record must be placed in the RECSIZE variable before the WRITE is issued.When reading a variable length record, the length of the record is delivered into the RECSIZE variable.The 01 Record description must be long enough to accommodate the largest record

Variable length Record ProcessingFD TRANFILE RECORD IS VARYING IN SIZE FROM 1 TO 80 CHARACTERS DEPENDING ON RECSIZE. 01 TRANREC PIC X(80). 88 END-OF-RECS VALUE HIGH-VALUES.

WORKING-STORAGE SECTION. 01 RECSIZE PIC 99.

READ TRANFILE AT END DISPLAY TRANREC(1:RECSIZE)

Writing Variable Length RecordsMany variable length records have a fixed front end, and varying numbers of segmentsFD CUST RECORD IS VARYING IN SIZE FROM 28 TO 408 CHARACTERS DEPENDING ON RECORD-LEN.01 CUST-REC. 05 ROOT-SEG. 10 CUST-NO PIC X(6). 10 INVOICE-COUNT PIC S99. 05 INVOICE-SEGMENT OCCURS 20 TIMES INDEXED BY NDX 10 INVOICE-DATE PIC X(8). 10 INVOICE-NO PIC X(5). 10 INVOICE-AMT pIC S9(5)V99.You must set the RECORD-LEN before writing the record!

AlternativeFD CUSTFILERECORD CONTAINS 20 TO 80 CHARACTERS01 REC. 05 FIXED-PART PIC X(20). 10 05 VARY-PART OCCURS 1 TO 6 TIMES DEPENDING ON COUNT INDEXED BY NDXCOUNT has to be initialized at the time of writing the record

Reading Variable Length Records FD CUST RECORD IS VARYING IN SIZE FROM 28 TO 408 CHARACTERS. 01 CUST-REC. 05 ROOT-SEG. 10 CUST-NO PIC X(6). 10 INVOICE-COUNT PIC S99. 05 INVOICE-SEGMENT OCCURS 20 TIMES INDEXED BY NDX 10 INVOICE-DATE PIC X(8). 10 INVOICE-NO PIC X(5). 10 INVOICE-AMT PIC S9(5)V99. PERFORM VARYING NDX FROM 1 BY 1 UNTIL NDX > INVOICE-COUNT ADD INVOICE-AMT(NDX) TO AMT-OWED END-PERFORM

EXERCISE #12Each A record for a given customer is followed by one to five B records for that customer.For each A record, write out one variable length record that contains the A record as the fixed part and the associated B records as the variable parts

EXERCISE #13BCST.SICCC01.PDSLIB(COBDATA5) CONTAINS TWO TYPES OF 80 BYTE RECORDS :

RECORD TYPE A1 BYTE TYPE CODE PIC X CONTAINING A5 BYTE CUSTOMER ID PIC X(5)

RECORD TYPE B1 BYTE TYPE CODE PIC X CONTAINING B5 BYTE PART NUMBER PIC X(5)6 BYTE COST PIC 9(4)V99

EXERCISE #14Read the variable length records you created in exercise #5. Produce a report similar to the one below:

CUSTOMER ID PART # COST 10030 22322 1,333.34 23444 3.44 50043 98.77TOTAL 1435.55 20030 22322 1,333.34 23444 3.44 50043 98.77TOTAL 1435.55

VSAM File ProcessingVirtual Storage Access Method

VSAM File TypesESDS Entry Sequenced Data SetAllows sequential processingRRDS Relative Record Data SetAllows sequential or random access by relative record numberKSDS Key-Sequenced Data SetAllows sequential, skip sequential, and random processing by key

VSAMVSAM data sets are known as ClustersFor ESDS or RRDS the cluster consists of a data componentFor KSDS the cluster consists of a data component and an index componentVSAM data is stored on DASD in control intervals which are grouped into control areas

VSAMThe Control Interval (CI) is the unit of data that transfers between the disk and virtual storageCI sizes are multiples of 2K with 4k being commonCIs can be constructed with free space to accommodate additions to the fileControl Areas (CA) can be constructed with free space to accommodate additions

VSAMVSAM dynamically manages the file by maintaining information in each CI and CAWhen a CI becomes too full the data it contains is split into two CIsWhen a CA becomes too full the data it contains is split into two CAsVSAM tries to keep records that are logically close together, physically close as well

VSAM Indexes

VSAM Components

Access Method Services (AMS)AMS is a VSAM utility that provides numerous optionsDEFINE CLUSTERPRINTREPROLISTCATDELETEDEFINE ALTERNATEINDEXDEFINE PATHBLDINDEX

VSAM JCLUnlike QSAM files, VSAM files are usually allocated in a separate job step before data can be written to the file A VSAM cluster is usually created by deleting and then defining the clusterAfter the cluster is defined, a job can run which writes data to the file

VSAM JCLParameters:INDEXED KSDSNONINDEXED ESDSNUMBERED RRDSKEYS ( len off) primary key infoCISZ (size) control interval sizeFREESPACE (ci ca) free space %s

MAKEKSDS 000100 //TSYSAD2C JOB 'YOUR NAME',USER=TSYSAD2,REGION=2048K,MSGCLASS=V 000200 //*MAIN CLASS=TSYSC,USER=TSYSAD2 000300 //DEFINE EXEC PGM=IDCAMS 000400 //SYSPRINT DD SYSOUT=* 000500 //SYSIN DD * 000600 DELETE TSYSAD2.PAYROLL.MASTER 000700 DEFINE CLUSTER - 000800 (NAME(TSYSAD2.PAYROLL.MASTER) - 000900 INDEXED - 001000 RECORDSIZE(31 31) - 001100 KEYS(5 0) - 001200 MGMTCLAS(STANDARD) - 001210 FREESPACE(0 0) - 001220 SHAREOPTIONS (3 3)) - 001230 DATA (NAME(TSYSAD2.PAYROLL.MASTER.DATA) - 001240 TRK(1 1) - 001250 CONTROLINTERVALSIZE(4096)) - 001260 INDEX (NAME(TSYSAD2.PAYROLL.MASTER.INDEX) - 001270 TRK(1 1)) 001280 /*

IDCAMS PRINT000100 //TSYSAD2P JOB 'A.STUDENT',USER=TSYSAD2,REGION=2048K,MSGCLASS=V 000200 //*MAIN CLASS=TSYSC,USER=TSYSAD2 000210 //* THIS IS AN IDCAMS PRINT 000220 //PRINT EXEC PGM=IDCAMS 000230 //SYSPRINT DD SYSOUT=* 000240 //SYSIN DD * 000250 PRINT INFILE(IFILE) - 000251 DUMP 000252 /* 000253 //IFILE DD DSN=TSYSAD2.PAYROLL.MASTER,DISP=SHR 000254 //

IDCAMS REPRO 000100 //TSYSAD2R JOB 'A.STUDENT',USER=TSYSAD2,REGION=2048K,MSGCLASS=V 000200 //*MAIN CLASS=TSYSC,USER=TSYSAD2 000210 //* THIS AN IDCAMS REPRO 000220 //REPRO EXEC PGM=IDCAMS 000230 //FILEIN DD DSN=TSYSAD2.PGM1.RESULTS,DISP=SHR 000240 //FILEOUT DD DSN=TSYSAD2.I10.PGM1.RESULTS,DISP=(NEW,CATLG,DELETE), 000250 // UNIT=SYSDA,DCB=(RECFM=FB,LRECL=80), 000251 // SPACE=(TRK,(1,1),RLSE) 000252 //SYSIN DD * 000253 REPRO - 000254 INFILE(FILEIN) - 000255 OUTFILE(FILEOUT) 000256 /* 000257 //AMSDUMP DD SYSOUT=* 000258 //

Creating a VSAM File 000100 IDENTIFICATION DIVISION. 000200 PROGRAM-ID. VSAM1. 000300 ENVIRONMENT DIVISION. 000400 INPUT-OUTPUT SECTION. 000500 FILE-CONTROL. 000600 SELECT PAYROLL-MASTER-OUT ASSIGN TO PAYMASTO 000610 ORGANIZATION IS INDEXED 000620 ACCESS IS SEQUENTIAL 000630 RECORD KEY IS ID-OUT 000640 FILE STATUS IS PM-STATUS. 000700 SELECT PAYROLL-MASTER-IN ASSIGN TO PAYMASTI.

Creating a VSAM File 004410 01 PM-STATUS. 004430 05 PM-STAT1 PIC X. 004440 05 PM-STAT2 PIC X. 004441 PROCEDURE DIVISION. 004450 OPEN INPUT PAYROLL-MASTER-IN 004460 OPEN OUTPUT PAYROLL-MASTER-OUT 004461 IF PM-STATUS NOT = '00' 004462 PERFORM 300-PRINT-STATUS 004463 END-IF 004470 PERFORM UNTIL ARE-THERE-MORE-RECORDS = 'NO ' 004480 READ PAYROLL-MASTER-IN 004490 AT END 004500 MOVE 'NO ' TO ARE-THERE-MORE-RECORDS 004600 NOT AT END 004700 PERFORM 200-READ-MODULE 004800 END-READ 004900 END-PERFORM 005000 CLOSE PAYROLL-MASTER-IN 005100 PAYROLL-MASTER-OUT 005110 GOBACK

Creating a VSAM File 005130 200-READ-MODULE. 005410 MOVE ID-IN TO ID-OUT 005420 MOVE NAME-IN TO NAME-OUT 005430 MOVE HOURS-IN TO HOURS-OUT 005440 MOVE RATE-IN TO RATE-OUT 005500 WRITE MASTER-REC-OUT 005510 IF PM-STATUS NOT = '00' 005520 PERFORM 300-PRINT-STATUS 005530 END-IF 005600 . 005700 300-PRINT-STATUS. 005800 DISPLAY 'FILE STATUS CODE:' PM-STATUS 005900 GOBACK 006000 .

VSAM Error StrategyVSAM returns a status code after each operationIt is imperative that you check each status code after each operation to insure that the program is proceeding normallyThe status code is a two byte field

OPENOPEN INPUT file-name OPEN OUTPUT file-name OPEN I-O file-name OPEN EXTEND file-name For EXTEND, access mode must be sequential

Reading for Sequential AccessREAD file-name [NEXT] [RECORD] [INTO data-name] [AT END imperative stmt] [NOT AT END imperative stmt][END-READ]Specify NEXT if access is DYNAMIC and you want sequential processingCan be omitted when access is SEQUENTIALINTO provides move mode I/OOmitting INTO provides locate mode I/O

Reading for Random AccessREAD file-name [RECORD] [INTO data-name] [INVALID KEY imperative stmt] [NOT INVALID KEY imperative stmt][END-READ]Be sure to set the key of the record you wish to read beforehand

Writing WRITE record-name [FROM data-name] [INVALID KEY imperative stmt] [NOT INVALID KEY imperative stmt][END-WRITE]

KSDS FILE CREATIONSELECT INVMAST ASSIGN TO INVMAST ORGANIZATION IS INDEXED ACCESS IS SEQUENTIAL RECORD KEY IS ITEM-NO FILE STATUS IS FILE-STAT.FD INVMAST01 RECORD-AREA. 05 ITEM-NO PIC X(5) 05 PIC X(75).WORKING-STORAGE SECTION01 FILE-STAT PIC X(2).

KSDS File CommandsOPEN INPUT file-nameOPEN OUTPUT file-name

READ file-name [NEXT] RECORD [INTO data-area] [AT END imperative] [NOT AT END imperative][END-READ]

KSDS File CommandsWRITE record [FROM]] data-name] [INVALID KEY imperative] [NOT INVALID KEY imperative][END-WRITE]

REWRITE record [FROM]] data-name] [INVALID KEY imperative] [NOT INVALID KEY imperative][END-REWRITE]

CLOSE file-name

KSDS File StatementsSTART file-name KEY IS = data-name > >= [INVALID KEY imperative] [NOT INVALID KEY imperative][END-START]

KSDS File StatementsDELETE file-name RECORD [INVALID KEY imperative] [NOT INVALID KEY imperative][END-DELETE]

Exercise #15Read BCST.SICCC01.PDSLIB(COBDATA6)COL 1-5 KEYCOL 6-25 NAMEAllocate a KSDS with record size 25 and a key field in cols 1-5Write out a KSDS record for each record in the file. Write out the records sequentially.

Exercise #16Read BCST.SICCC01.PDSLIB(COBDATA7)COL 1-5 KEYRead a KSDS record (randomly) for each record in the file. Write out the names you find sequentially. If the record doesnt exist, print a message Not Found

Nested ProgramsCOBOL programs can be nested. There are many advantages for doing this:The monolithic working storage of most COBOL programs leads to difficulty in debugging because all data is globalNested programs break the working storage into smaller areas that can only be accessed by programs that need access. Nested programs provide for parameter passing by techniques found in all modern languages (by value, by reference)There is no execution degradation because of nested programs. In fact, calling a nested program is more efficient than calling a separately compiled program.

Nested ProgramsCalling a nested program is as efficient as performing a paragraphNested programs provide design flexibility and encourage good program designA nested program would be called a function or subroutine in any other languageNested programs unleash the power of COBOL pointers and allow COBOL programmers to design data structures that encourage efficient programming techniques

Nested ProgramsPROGRAM-ID. MAIN.

PROGRAM-ID. SUB1.

END PROGRAM SUB1.PROGRAM-ID. SUB2END PROGRAM SUB2.END PROGRAM MAIN.

COBOL Pointers05 PTR1 USAGE IS POINTER. 05 PTR2-P USAGE IS POINTER VALUE NULL.SET PTR1 TO ADDRESS OF LINKAGE-THINGSET PTR2 TO PTR1LINKAGE SECTION. 01 NAME-STRUCTURE. 05 FIRST-NAME PIC X(18). 05 LAST-NAME PIC X(26).

SET ADDRESS OF NAME-STRUCTURE TO EXAMPLE-P.

COBOL PointersIF PTR1 NOT = NULL AND PTR1 NOT = PTR2 PERFORM 2730-SOMETHINGEND-IF

SYNCHRONIZEDThe SYNCHRONIZED clause is sometimes used with USAGE IS COMP or USAGE IS INDEX items. It is used to optimize speed of processing but it does so at the expense of increased storage requirements.

The word SYNC can be used instead of SYNCHRONIZED

SYNCHRONIZED causes slack bytes to be generated when needed.

*********************