Bill,

Thanks for the sound advice.  This is a structurally complex batch application 
with many calls and many subprograms.  SSRANGE might be helpful, as a careful 
review of the subprogram code has revealed no obvious issues like that so far.

I am already running a test compile of the failing subprogram with tests of the 
storage being overlaid at the start of the program, so I get messages displayed 
when it is detected at program entry, but by then it is too late.

The local 0C7 dump formatter has given me the contents of what gets 
overwritten, but so far it is not very helpful (one 'N' and a bunch of spaces 
with no obvious culprit to have done that).

What I am afraid is happening is that another subroutine (there are 30+ 
involved) has a previously undetected really wild subscript/index error and 
does the overlay.  Only a SLIP can catch that, or universal use of SSRANGE in 
every program in the application.  Which I might be forced to use.

Thanks again for your help.

Peter

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf 
Of Bill Woodger
Sent: Friday, October 21, 2016 2:20 PM
To: [email protected]
Subject: Re: Tool to detect virtual storage overlay in an address space?

Are you able to change the program?

Are you able to compile with SSRANGE?

Are there any CALLs to the program, or by the program?

SSRANGE will take care of any reference-modification/subscripting in the 
program in question.

Test the storage (that you know gets whacked) on arrival and prior/post any 
CALLs. You should be able to narrow down where to look, and narrow further in 
that.

Also useful (for you) to know what it gets overwritten by, and what value that 
has.

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