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DSPSIZE Parameter

 
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Oldie
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Joined: 19 Dec 2002
Posts: 10
Topics: 3
Location: Munich, Germany

PostPosted: Fri Jun 20, 2003 5:46 am    Post subject: DSPSIZE Parameter Reply with quote

I would like to optimize the CPU consumption of a DFSORT job.
I have studied the handbooks, and found the valuable runtime parameter

--------------------------------------------------------------------------------
DSPSIZE=MAX
--------------------------------------------------------------------------------

It decreases the CPU time "dramatically" (not my own words...).
But now, the systems programmer says there's a problem by using this param - it goes as far as crashing the system down !
Is it true ? We are using

- MVS VERSION SP7.0.4
- DFSORT REL 14.0

Oldie
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Frank Yaeger
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Joined: 02 Dec 2002
Posts: 1618
Topics: 31
Location: San Jose

PostPosted: Mon Jun 23, 2003 3:46 pm    Post subject: Reply with quote

Oldie,

DSPSIZE=MAX allows DFSORT to use the optimal data space for an individual sort run. Since DFSORT prefers to use hipersorting and also queries system resources, this parameter should not 'crash' your system unless you have hipersorting turned off and are submitting several large sorts that use a large amount of dataspace on a small system all at the same time. The likelihood of this happening is very small. Note that DSPSIZE=MAX is the IBM-supplied default.

DSPSIZE=MAX will not necessarily be the best way to improve CPU time for a particular job; in fact, depending on how the job is currently running, DSPSIZE=MAX may not improve CPU time at all.

If you want the DFSORT Team to do an analysis of your job to determine if there's something you can do to improve its CPU time, add the
following to your job:

Code:

//SORTDIAG DD DUMMY


Rerun it and send me the JES and DFSORT messages offline (yaeger@us.ibm.com).
_________________
Frank Yaeger - DFSORT Development Team (IBM)
Specialties: JOINKEYS, FINDREP, WHEN=GROUP, ICETOOL, Symbols, Migration
DFSORT is on the Web at:
www.ibm.com/storage/dfsort
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