On Wed, 11 Apr 2012 10:24:10 -0400, Mark Jacobs <mark.jac...@custserv.com> 
wrote:

>We had a discussion yesterday regarding our obsolete IEFUSI exit and how
>it should be modernized to even know about the virtual storage region
>above the 2GB line.
>
>One of the concerns was that since IEFUSI has no practicable effect on
>authorized programs I was asked to come up with some ways to better
>manage our environment just in case some user decides to allocate and
>start using massive amounts of above the bar storage.
>
>My question to the mailing list is do you manage towards this scenario
>and if so, how?
>

I'm not really worried about STCs and authorized users.  Nothing I can do 
about them except allocate 2000 page volumes (just kidding).   

The comments in my IEFUSI exit from 2005 still hold true and explain
what I am doing.  So far, it has worked out fine.   My client does have
64-bit usage and also large pages running 64-bit WebSphere.  
Basically, I just want to keep someone from "playing" with 64-bit
from destroying the system. 

My SMFPRMxx MEMLIMIT is to 10G.   

9/14/2005   M ZELDEN     FORCE MEMLIMIT OF 5G FOR ANY JCL       
                         SPECIFICATION OF ANYTHING OVER 5G BUT  
                         ALLOW MEMLIMIT NOLIMIT (16383PB) IF    
                         REGION=0M. IF NO JCL SPECIFICATION IS  
                         USED (OTHER THAN REGION=0M), THEN TAKE 
                         THE MEMLIMIT DFLT FROM SMF (SMFPRMXX). 
                         THIS WILL ALLOW SYSTEMS THAT NEED A    
                         HIGHER MEMLIMIT TO HAVE SMFPRMXX BE    
                         THE CONTROLLING FACTOR - AS LONG AS    
                         MEMLIMIT IS NOT SPECIFIED IN THE JCL.  
                         SINCE ONLY STCS CAN USE REGION=0M, ONLY
                         STCS WITH REGION=0M CAN GET MORE THAN  
                         THE FORCED MEMLIMIT OR THE SMF DFLT.   

By having SMFPRMxx be the controlling factor, I could easily raise it
if a problem came up with no JCL changes etc.   So far, I've haven't
needed to do that.     Keep in mind I updated this exit for the brave
new world in 2005.   I'm slightly surprised it's been 7 years and
I haven't needed to modify it except for a change in 2007 related to 
OA14391 which affected z/OS 1.7 & z/OS 1.8 and above. That
APAR kept STCs with REGION=0M from  getting MEMLIMIT=NOLIMIT
so I updated the exit to force MEMLIMIT=NOLIMIT for STCs with
REGION=0M (which was the behavior prior to OA14391).

Regards,

Mark
--
Mark Zelden - Zelden Consulting Services - z/OS, OS/390 and MVS       
mailto:m...@mzelden.com                                        
Mark's MVS Utilities: http://www.mzelden.com/mvsutil.html 
Systems Programming expert at http://expertanswercenter.techtarget.com/

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