Not a huge expert but I do a certain amount of tuning of storage requirements 
as the developer of a vendor product, and I have the distinct impression that 
LE's initial program runtime storage parameters are fixed at either compile or 
startup time and based on supplied parameters, independent of the actual region 
size. That is, there is no algorithm like "get half the free storage." It is 
"get X bytes."

Of course, region size affects the possibility of an x78 failure if the program 
requires more storage than initially obtained.

I notice the OP, who was posting hourly or so, has gone quiet. Perhaps the 
problem has been located.

Charles


-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf 
Of David W Noon
Sent: Tuesday, July 25, 2017 8:57 AM
To: [email protected]
Subject: Re: REGION=0M leads to CPU through the roof

On Tue, 25 Jul 2017 08:40:25 -0500, Tom Marchant
([email protected]) wrote about "Re:
REGION=0M leads to CPU through the roof" (in
<[email protected]>):

[snip]
> I agree. Increasing the region doesn't ordinarily increase the storage 
> utilization.

As a PL/I programmer of more than 40 years, I am sufficiently familiar with 
IBM's run-time libraries to offer a contrary experience. The start-up code for 
the old PL/I OS Optimizing compiler would check the VSM parameters and GETMAIN 
50% of the remaining storage in the region/partition. [I wrote "partition" 
because this goes back to the
OS/VS1 days.] The upshot was that the bigger the region one coded in the JCL 
the more memory the RTL would acquire at start-up time -- and would hold for 
the duration of the job step. It could acquire still more if the program needed 
it.

One could override this by coding a PLIXOPT string in the OPTIONS(MAIN) 
procedure or by putting similar options in the PARM field of the JCL.

Since LE is largely analogous to the old PL/I RTL, I would bet dollars to 
doughnuts that it will do something similar if allowed. Coding memory 
constraints in the RTL options can work wonders.

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