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Exclusive control of dataset


IBM Mainframe Forums -> JCL & VSAM
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Jasand

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Joined: 23 Jan 2009
Posts: 32
Location: Tamil nadu

PostPosted: Tue Feb 15, 2011 4:24 pm
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Hi,

Could somebody let me know how to get exclusive control of a dataset for a job ? (Any method other than using DISP=OLD to get the exclusive control of the dataset).

The issue with using DISP=OLD(Job A) is that, when another job(Job B) with DISP=SHR access is already running, there occurs contention between the 2 jobs. Please correct me if I am wrong.
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enrico-sorichetti

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Joined: 14 Mar 2007
Posts: 10873
Location: italy

PostPosted: Tue Feb 15, 2011 4:38 pm
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all happens according to the ENQueuing rules of JCL

if You want exclusive control of a resource ( any resource ) You want exclusive control.
no more, no less, and if somebody else is using that same resource You will have to wait until that somebody else has released it
( the happening is commonly known as resource contention )

here are the links to the relevant jcl manulas
z/OS V1R6.0-V1R10.0 MVS JCL User's Guide
publibz.boulder.ibm.com/cgi-bin/ ... 0712160458
and here
z/OS V1R10.0 MVS JCL Reference
publibz.boulder.ibm.com/cgi-bin/ ... 0604022956

to avoid a visible resource contention use Your scheduler facilities to serialize
( the contention will still be there, but You will not get any console messages,
the only evidence will be found by running a contention/delay report)
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Jasand

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Joined: 23 Jan 2009
Posts: 32
Location: Tamil nadu

PostPosted: Tue Feb 15, 2011 4:44 pm
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Thank you for your quick response. Will check the manuals.
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Phrzby Phil

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Joined: 31 Oct 2006
Posts: 1042
Location: Richmond, Virginia

PostPosted: Tue Feb 15, 2011 5:54 pm
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Enrico's answer is complete Jasand.

But I'm wondering, from the way you identified a seeming "problem" with DISP=OLD, exactly why you thought that behavior (having to wait for the DISP=SHR job to finish) was not what you wanted.
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Robert Sample

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Joined: 06 Jun 2008
Posts: 8696
Location: Dubuque, Iowa, USA

PostPosted: Tue Feb 15, 2011 5:58 pm
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I wondered that too, Phil, but I've learned there are some questions not worth asking ... that one got borderline! icon_smile.gif
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enrico-sorichetti

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Joined: 14 Mar 2007
Posts: 10873
Location: italy

PostPosted: Tue Feb 15, 2011 6:05 pm
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I sometimes wonder too... about my good character icon_biggrin.gif

really I sometimes answer in what I hope is an exhaustive way in order to,
answer one... speak to many
but sadly it looks like that most of the times it is not worth the effort icon_sad.gif
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