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RDz Workbench – Debugging z/OS COBOL ApplicationsRDz Workbench – Debugging z/OS COBOL Applications

Batch COBOL Debugging WorkshopBatch COBOL Debugging Workshop

Jon Sayles, Rational System z Products - jsayles@us.ibm.com

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Using this PowerPoint Slide DeckThere are two types of slides in this PowerPoint:

1. Workshop slides: These are slides that will help you master RDz through technical

development techniques and hands-on exercises

Workshop slides have this character: in the slide header– Note that some workshop slides have the word "Workshop" in the slide header

– However all workshop slides have the character in the slide header

2. Learning content: Any slide that doesn't contain a character in the slide header contains

conceptual learning material– To be read for understanding– Often these slides are preparation for the workshop exercises that follow

There are additional Powerpoint slides that contain deep RDz learning content, without exercises and without lab instructions If you want to learn more about any particular RDz topic, you can

learn more about it from the Powerpoint slides.

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Pre-Workshop Overview You will use Debug Tool to test the SAM1 and SAM2

batch COBOL programs Steps:

Allocate data setsModify the JCL for the compile and run stream JCLFind your workstations:

I/P Address Port#

Substitute those variables into the run steam JCLDebugTest out various Debug Tool options

At any point, you can terminate your debug session by clicking the Red icon or pressing Ctrl+2Ctrl+2And you can re-submit the JCL again – to Debug (again)

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Workshop – Preparing for the Workshop Prerequisites:

Ensure the IBM Debug Tool is installed and configured on your z/OS You may need to speak to one of your systems programmers about this

Ensure that you have a "real" I/P address (as opposed to a router-generated I/P address) for your workstation

Ensure that you know the location (system library) of the COBOL compiler IGYCRCTL – typically found in: COBOL.VnRn.COBOLCOBOL.VnRn.COBOL - - Example: COBOL.V3R4.COBOLCOBOL.V3R4.COBOL

Locate the files: COBOL programs:

SAM1 SAM2

COBOL copybooks: TRANREC CUSTCOPY

JCL: SAMCMPLK XSAM

You will need access to a QSAM test data file: SAMFILE <HLQ>.TEST1.SAMFILE This file is in the \data folder of your RDzClass.zip file – that you used to setup for

these workshops. You will need to transfer the file to the mainframe, ensuring its DSORG/LRECL/BLKSIZE is maintained

SAMFILE properties

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You will need the following standard development libraries for Compile/Link-Edit: <HLQ>.xxx.COBOL – example: DDS0001.TEST.COBOL <HLQ>.xxx.COPYLIB – example: DDS0001.TEST.COPYLIB <HLQ>.xxx.LISTING – example: DDS0001.TEST.LISTING <HLQ>.xxx.OBJ – example: DDS0001.TEST.OBJ <HLQ>.xxx.LOAD – example: DDS0001.TEST.LOAD

If you haven't already allocated these libraries, pleas allocate them now.

Hint: Specify characteristics by usage type:Will allow you to select the correct DCB for the filesGive each dataset 5 primary and 5 secondary TRKS of

disk space

Workshop – Allocate Data Sets

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Workshop – SAM1 and SAM2 Code Review Load both SAM1.cbl and SAM2.cbl into the editor – and review the logic in this

typical z/OS data collections/editing/report writing pattern Time permitting, learn a little bit about the programs you're going to debug, using a

few of the RDz code analysis tools & techniques: Multiple editing windows to study the logic, Program Control Flow, Perform

Hierarchy, navigation techniques, Hover, etc.

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Workshop – Compile SAM1 and SAM2

Steps (in SAMCMPLK.jcl):

In all fourfour job steps, modify the library names for: COBOL compiler library Your personal datasets

Submit the JCL Go to the JES queue and check the

return codes for each step

Optionally, expand your load library and ensure that there are members for SAM1 and SAM2

Note – this step requires you to have allocated all of the datasets referenced in the JCL (see prior slide)

Don't forget the 2nd LKED step

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Switch to the Debug perspective

Click on the downward pointing triangle to the right of the little green listener tool, and:Note the Port#Select and copy the I/P address

Ensure that green listener tool is – in fact – green, and not red. If it's red (not listening) click it (once) to change it to green

Workshop – Obtain your I/P Address and Port#

This is the I/P address you want!

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Open XSAM.JCL and modify:JOB card

You will have to enter your shop's specific JOB card parameters

Your test dataset names: Load library The SAMFILE dataset DSN

//CUSTFILE DD DSN=…

Paste your copied IP address – between the && and %%

Also verify (or change) the Port # to your RDz client listener port (recall from previous slide)

Submit the job:Click YesYes to enter the Debug Perspective

Workshop – Modify and Submit the Run JCL

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Begin using the Debug Tool functions that you learned about in this section: Press F5 – or click Step Into a few times – note that the Outline view synchronizes with your source Right-click over variable in Variables – and select 2. Automonitor Previous – step a few more times Hover over a variable in the PROCEDURE DIVISION Try some find commands – in the ISPF command line area of SAM1.cob Navigate around the source code using the Outline view Press F6 – a few times. It will act the same as F5 until you get to a CALL statement

Workshop – Debug Techniques – Stepping

Hover over a variable

Hover over a variable

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Change some values: From the Variables tab:

Filter Locals > 0 ALL– What does this do?

Click inside a variable and change its value Press Enter to save your change

Change the representation of several fields to Hexadecimal Try editing in Hex

– Change a binary numeric field value to negative– Etc.

Workshop – Debug Techniques – Variables

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From within VariablesFrom within Variables Select Monitor Local Variable

Check the MonitorsMonitors view

Experiment with: Change representation Change Value… Show Type Names Remove

Workshop – Debug Techniques – Monitors

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Workshop – Monitors (more techniques) From MonitorsFrom Monitors

Select Detached

Drag the Monitors view around to make the best use of "screen real estate"

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Set and use breakpointsSet and use breakpoints Find the CALL to 'SAM2' Add a breakpoint by either:

Double-clicking in the prefix area – or: Right-click over the statement and

select Add Breakpoint Resume (F8) to the breakpoint Click into 'SAM2'

RDz will take a few seconds to load SAM2 Debug into the program a few clicks Press F7 – to return to 'SAM1' Resume (F8) to the breakpoint Press F6 – What does this do?

Answer – runs all of the code in SAM2, and stops at the Next Sequential Instruction after the call

Double-click on TRAN-KEY to select the field Right-click and select: Add Watch Breakpoint Resume (F8) until the value in TRAN-KEY changes, and the

breakpoint causes your program to stop

Workshop – Debug Techniques – Breakpoints

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Terminate your debug session

Submit XSAM JCL again

Remove all Breakpoints

Add a Breakpoint to the PERFORM 720… statement in 200-PROCESS-UPDATE-TRAN

Edit that Breakpoint, and make it conditional At the wizard click Next > Specify the following Expression: Click Finish

Resume(F8) - you should stop at the conditional Breakpoint on line 404 Click the Debug Console view – to verify

Workshop – Debug Techniques – Breakpoints continued

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Terminate your debug session Submit XSAM JCL again Remove all Breakpoints From the Debug Console

issue the following Debug Engine Command:

set automonitor on log

Click Animated Step Into Follow the trace in the Debug

Console

Click Animated Step Into

Optional: Right-click in the Debug

Console and Export History – for your debug trace

Workshop – Debug Techniques – Breakpoints continued

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Branching and testingBranching and testing Use the Outline view to navigate to 730-READ-CUSTOMER-FILE Right click on the EVALUATE statement

and in the prefix area (on the left) select Jump to Location

What did this do? Answer: Set the current instruction pointer

to the line

Mouse over WS-CUSTFILE-STATUS and note its current value Double-click WS-CUSTFILE-STATUS and select Monitor Expression From the Monitors view, change the value of the field to 04 Step through the code, what happens?

Answer #1: Program execution "falls thru" – why? Answer #2: Jump To Location breaks the logic out of the "Perform chain" (dependent

PERFORM'd paragraphs) routines in your paragraph logic Return to the EVALUATE statement via Jump To Location From the Monitors view, change the value of WS-CUSTFILE-STATUS to 0909 Step through the code – note the logic flow

Terminate your debug session

Workshop – Jump To Location

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Time permitting – submit the JCL again, and try:

Setting conditional breakpoints Unsetting breakpoints

Uncheck the box Single Remove All

Run until SAM2 abends Click Examine Click OK

What does Examine do?

Submit the JCL again, use: Run to Location

How does this differ from Jump to Location?

Workshop – Experiment !

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Workshop – Optional Workshop (force an ABEND)If your debugging hasn't yet hit an ABEND condition, try forcing one by doing

the following:

From SAM1.cbl Add these two variables in the

WORKING-STORAGE SECTION.

Add these two statements in 710-READ-TRAN-FILE.

Save your changes to SAM1.cbl

Submit SAMCMPLK.jcl – check the return codes in JES

Submit XSAM.jcl, and from your Debug session: Set a breakpoint at MOVE SPACES TO ABEND-TEST. (F8) Resume to the breakpoint. (F5) Step into the ABEND Click Examine