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SortWork Area in JCL


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Pons

New User


Joined: 25 May 2007
Posts: 61
Location: Coimbatore

PostPosted: Mon Aug 08, 2011 8:51 pm
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Hi,

I need some clarification on Sort Work Area. As per my understanding, if the input file is huge, the explicit sort work area is required. For small files, system allocated default work area is enough.

Is this correct? If so, suppose, what is the disadvantage of providing explicit workarea for small files (Even that is not required).

Please advise. Thanks.
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Bill Woodger

Moderator Emeritus


Joined: 09 Mar 2011
Posts: 7309
Location: Inside the Matrix

PostPosted: Mon Aug 08, 2011 9:22 pm
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If Dynamic sort work areas can be specified, that will be best - let the product allocate what it needs.

Otherwise you end up with tiny sorts have excessive DASD allocation, but only using a fraction.

If you specify sortwork when it is not needed, I suspect it will not use the sortwork you supply.
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Pons

New User


Joined: 25 May 2007
Posts: 61
Location: Coimbatore

PostPosted: Tue Aug 09, 2011 4:18 am
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Oh. Is it so. I thought sork work area will be allocatted before it execute the sort utility.
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dbzTHEdinosauer

Global Moderator


Joined: 20 Oct 2006
Posts: 6966
Location: porcelain throne

PostPosted: Tue Aug 09, 2011 4:25 am
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Pons wrote:
Oh. Is it so. I thought sork work area will be allocatted before it execute the sort utility.


Bill,

the above response is typical of someone who does not know,
but will argue with you about your answer.

Pons,

suggest you refer to the user guide for whichever sort product you have.

the kind of information you are looking for is always in the manuals,
and then you would know, without asking and arguing.
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Frank Yaeger

DFSORT Developer


Joined: 15 Feb 2005
Posts: 7129
Location: San Jose, CA

PostPosted: Tue Aug 09, 2011 4:43 am
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If you specify a SORTWKdd DD statement, the system allocates the primary work space for it before DFSORT is invoked. DFSORT may or may not use all of the primary and may or may not get secondaries. So you can end up allocating space that isn't used.

If you don't specify SORTWKdd DD statements (or your site's installation default is set to deallocate them), DFSORT will use dynamic allocation of work data sets. DFSORT will adjust the allocated work space to what it thinks is needed. So you can still end up allocating space that isn't used, but the allocation is more flexible.

We recommend the use of dynamic allocation of work space. You can specify up to 255 dynamically allocated work data sets, so very large files can be accommodated.

For more information on DFSORT work space, see:

publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/ICE1CA50/A.0?DT=20100630155256
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