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abhayasahoo · Beginner Joined: 04 Dec 2002 Posts: 8 Topics: 6

Hi,

Is it advisable to put REGION=0M in all the jobs in the shop ? Let's say that program A does not require enough virtual storage. Does it still allocate unwanted virtual storage for the program ?

We have been facing problems with S878 abends in many of our jobs. We have been asked to put REGION=0M in all of our jobs. I just wanted to know if this would impact the performance of other jobs executing under the same CPU.

Regards,
Abhaya

kolusu · Posted: Sun Dec 08, 2002 3:29 am Post subject:

abhayasahoo,

The region size is the amount of storage in the user region available to the job, started task, or TSO/E user. The system uses region size to determine the amount of storage that can be allocated to a job or step when a request is made using the STORAGE or GETMAIN macros and a variable length is requested. The region size minus the amount of storage currently allocated, determines the maximum amount of storage that can be allocated to a job by any single variable-length GETMAIN request.

If no REGION parameter is specified, the system uses the REGION parameter specified on each EXEC statement. If no EXEC statement REGION parameter is specified, the system uses a job step installation default specified at JES initialization.If your installation does not change the IBM-supplied default limits in the IEALIMIT or IEFUSI exit routine modules, then specifying various values for the region size have the following results:

A value equal to 0K or 0M -- gives the job all the storage available below and above 16 megabytes. The resulting size of the region below and above 16 megabytes is installation-dependent.
A value greater than 0K or 0M and less than or equal to 16,384K or 16M -- establishes the size of the private area below 16 megabytes. If the region size specified is not available below 16 megabytes, the job abnormally terminates. The extended region size is the default value of 32 megabytes.
A value greater than 16,384K or 16M and less than or equal to 32,768K or 32M -- gives the job all the storage available below 16 megabytes. The resulting size of the region below 16 megabytes is installation-dependent. The extended region size is the default value of 32 megabytes.
A value greater than 32,768K or 32M and less than or equal to 2,096,128K or 2047M -- gives the job all the storage available below 16 megabytes. The resulting size of the region below 16 megabytes is installation-dependent. The extended region size is the specified value. If the region size specified is not available above 16 megabytes, the job abnormally terminates.

Hope this helps...

cheers

kolusu

warp5 · Posted: Mon Dec 09, 2002 2:13 am Post subject:

A point to add is that if a job region size is given and an exec region size is given the exec region size is ignored - the job region size overrides.

Bill Dennis · Posted: Mon Dec 09, 2002 9:02 am Post subject:

As a sysprog, I have seen system problems when a pgm loops aquiring storage and the user has set REGION=0M. We discourage Sad

the use of 0M.

Regards,
Bill

nxn00 · Posted: Tue Dec 10, 2002 11:58 am Post subject:

Using the LE parameter ALL31 can help your program run successfully.

See the following article:

www.naspa.com/PDF/99/T9903008.pdf

and link to LE manual:

http://publibz.boulder.ibm.com/cgi-bin/bookmgr_OS390/BOOKS/CEEA3130/CCONTENTS?SHELF=CEE2BK30&DN=SA22-7562-03&DT=20020625092930

Lots of luck! Very Happy

_________________
Natalie

abhayasahoo · Beginner Joined: 04 Dec 2002 Posts: 8 Topics: 6

Thanks for your replies.

Bill,

What system problems are encountered when one uses REGION=0M in all the jobs ? When all the jobs are coded with REGION=0M on the job card, does the system still allocate more than the required storage for the jobs ?

Anuj Dhawan · Posted: Wed Sep 30, 2009 1:25 am Post subject:

I'm reviving the mummies...but here is question left un-answered so thought to use my $ .02...hopefully I do not annoy anyone...

A value of 0K or 0M will allow the program to request the largest available region size, however this specification should be used with caution. From the OS/390 Initialization and Tuning Guide,

"The region size allowed to users can affect performance of the entire system. When there is no limit on region size and the system uses its default values, users might obtain so much space within a region (by repeated requests for small amounts of storage or a single request for a large amount) that no space would remain in the private area for system use. This situation is likely to occur when a program issues a request for storage and specifies a variable length with such a large maximum value that most or all of the space remaining in the private area is allocated to the request. If this program actively uses this large amount of space (to write tables, for example), it can affect central storage (also known as real storage) and thus impact performance."
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Regards,
Anuj

Bill Dennis · Posted: Wed Sep 30, 2009 8:02 am Post subject:

Anuj,

Thanks for reviving the mummy (that's a new one to me). I missed the question returned to me so many years ago. Glad you gave a response.
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Regards,
Bill Dennis

Disclaimer: My comments on this foorum are my own and do not represent the opinions or suggestions of any other person or business entity.

Anuj Dhawan · Posted: Wed Sep 30, 2009 10:43 am Post subject: