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CALL vs START vs LINK

 
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morfius9
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Joined: 22 Feb 2006
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PostPosted: Thu Jun 19, 2008 6:10 pm    Post subject: CALL vs START vs LINK
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Does anyone have any documentation about the different performances of CICS START/LINK & CALL commands?
I have a new program which would be called by a number of existing programs. I am at loggerheads whether to use a CALL or an EXEC CICS START or EXEC CICS LINK command. Can someone help me decide which is the command that would give the best performance?
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Bill O'Boyle

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Joined: 14 Jan 2008
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Location: Atlanta, Georgia, USA

PostPosted: Thu Jun 19, 2008 6:27 pm    Post subject: Re: CALL vs START vs LINK
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From a Main-Program -

01) A CALL to a sub-program is recommended providing that the sub-program is Called more than once.
02) A single LINK and a single Call to a sub-program are equivalent in overhead.
03) A START is a task which runs concurrently with the STARTER (IE: The Main-Program).

When you use a START, control will never be returned to the STARTER, as this is an Asynchronous/Concurrent task, unrelated to the Main-Program.

Otherwise, a CALL and a LINK will eventually return control to the Main-Program (IE: The LINKER/CALLER) and this process is Synchronous.

HTH....

Regards,

Bill
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UmeySan

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PostPosted: Thu Jun 19, 2008 6:28 pm    Post subject:
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Hi !

There is a difference between these two commands, START & LINK:

When a CICS program issues an EXEC CICS LINK command, control passes to a second program. The second program executes and, after completion, returns control back to the first program.

With the EXEC CICS START you're initiating another task.

Also look at EXEC CICS XCTL:
With that, you're terminating the current program and execute the one specified in the Command.
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UmeySan

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PostPosted: Thu Jun 19, 2008 6:32 pm    Post subject:
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@Bill:

Sorry, the time you where sending your message, i was still typing mine.
You already said it. I'm getting old and turning into grey.
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morfius9
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PostPosted: Thu Jun 19, 2008 7:07 pm    Post subject: Reply to: CALL vs START vs LINK
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Is there any extra overhead or over utilization of the resources that take place if i start say 10 transactions from the initiating program. i.e. In a loop, i have the CICS START commands that would be started with different data on each iteration of the loop?
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