Threadsafe by the book
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Transcript of Threadsafe by the book
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© 2012 IBM Corporation
CICS Lunch n LearnThreadsafe by the Book(The Redbook)
Gary Andrews
Client Technical Specialist: CICS Tools
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The BookSG24-6351-0*
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Agenda
Why Threadsafe
In The Beginning
Threadsafe Conversion Plan (and my Threadsafe experience)
Questions
Summary
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Why Threadsafe?
Save CPUTake advantage of modern: Hardware Design Software Design.
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In the Beginning Your applications were Sleek and
Fast
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Then your applications became popular. Volume increased. You added new functionality. But response time started to decline. Users complained.
How did you fix this mess?
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Many of us added hardware.
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And we took advantage of multiple engines in the new mainframe hardware.However, we migrated from a simple design……..
CICS RegionApplications
To split regions due to Virtual Storage Constraint
CICS RegionApplication 2
CICS RegionApplication 1
CICS RegionApplication 3
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And we added even more regions
Quality Assurance ProductionSystem Test
Development
Application 1
Application 2
Application 3
Application n
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As of CICSTS V2.2You have a 3rd option
Open Transaction Environment (OTE)
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Let’s review the steps of a Threadsafe project
Indentify Exits
Indentify high cpu/high TCB switching transactions
Indentify the programs used by those transactions and review
Mark reviewed programs as Threadsafe (Concurrency=Required (V4.2 and V5.1)
Validate your work.
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Indentify Exits• Global User Exits: Exec CICS Inquire Exitprograms
• Using Program DFH0STAT
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Indentify Exits• Identify homegrown and vendor exits
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Identify High CPU Transactions
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Or Identify High TCB Switching Transactions
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Now Let’s Identify the Programs Used by Our Target Transactions
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After Review Change Concurrency of the Program to either Threadsafe (prior to V4.2) or Required (V4.2 and newer)
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Now Let’s Verify Our Work (Part 1)
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Now Let’s Verify Our Work (Part 2)
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QR TCB
L8 TCB
(1) (2) (1) (2)
CICS TS V4.1 Threadsafe CICSAPI
QR TCB
L8 TCB
(2) (3) (2) (3)
CICS TS V4.2 Threadsafe Required
CICS TS V5.1 Threadsafe RequiredL8 TCB
(1) Changemode due to DB2 call
(2) Changemode due to TD Write
(3) Changemode back to L8 due to Required option
What is Concurrency=Required?
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If you did a Threadsafe Conversion Prior to CICSTS V4.2
• After you install V4.2 or V5.1
• Review your program definitions.
• Consider changing
• Concurrency=Threadsafe to
• Concurrency=Required
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Consider This: Are these transactions Threadsafe Candidates?
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What would happen if they were Threadsafe?
• No immediate CPU savings
• Greater throughput for important transactions
• Free up the QR TCB
• Opens the possibility of region consolidation.
• Region consolidation = CPU savings!!!
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SummaryThreadsafe Project Steps
Indentify Exits
Indentify high cpu/high TCB switching transactions
Indentify the programs used by those transactions and review
Mark reviewed programs as Threadsafe (Concurrency=Required (V4.2 and V5.1)
Validate your work.
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You want to transition from this
QR TCB
TCB Switching
L8 TCB’sL8 TCB’s
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To ThisAll Important Transactions do not switch off the L8 TCBs
L8 TCB’sL8 TCB’s L8 TCB’s
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Find out more
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