Rob,

The short answer is yes. Prior to purge D GRS displays waiters and after the 
purge D GRS display no contention so I confident all requestors latches are 
being purged.

Are all the latches purged by your EOT exit owned by RBs in the latch set 
creators home address space or by the terminating TCB?  We are attempting to 
purge latches held by a space switched PC across address spaces and I believe 
purge is not behaving the way I initially interpreted the documentation in this 
environment.    

Michael Cittadino
CA Technologies

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf 
Of Rob Scott
Sent: Thursday, July 12, 2012 4:52 PM
To: [email protected]
Subject: Re: z/OS latch problem

Michael

Are you sure the requestor ID on the latch purge is the same as that used on 
the latch obtain ?

I have been using latch services with a failsafe purge performed by the TCB EOT 
exit routine for some time without obvious problems.

Rob Scott
Lead Developer
Rocket Software
77 Fourth Avenue . Suite 100 . Waltham . MA 02451-1468 . USA
Tel: +1.781.684.2305
Email: [email protected]
Web: www.rocketsoftware.com


-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf 
Of Cittadino, Michael A
Sent: 12 July 2012 18:39
To: [email protected]
Subject: z/OS latch problem

We are introducing latches into an application on z/OS 1.13 and have 
encountered behavior that does not match our interpretation of the 
documentation.

In the z/OS MVS Programming: Authorized Assembler Services Guide the 
description of the latch purge service states that latch purge "purges all 
granted and pending requests". From this our understanding is that latch purge 
acts as a general latch release and we expect that if we have a set of waiters 
for a latch and purge the latch set that the waiters would have their latches 
released and resume execution.

If we have a set of processes with a latch owner and a set of waiters and we 
iterate over the set and issue ISGLREL for each process as it has ownership the 
processes will resume execution.

However when we issue latch purge it completes rc 0 and the D GRS,LATCH display 
shows no latch contention but the RBs for the latch waiters remain paused and 
the processes do not resume execution. This occurs for both ISGLPRG and ISGLBPA.

At this point we are not sure if the latch purge behavior is a defect or if the 
actual behavior is different from our interpretation of the documentation.

Michael Cittadino
CA Technologies

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