On 7/19/2011 1:37 PM, Gary DiPillo wrote:
We don't need to discuss RENT and REFR, but I certainly need to read up on
them again. I'm sure that what I remember and what is true have long ago
drifted apart.
REFR modules are not allowed to update themselves.
It's widely believed that RENT modules had the same restriction, but that's not
entirely true. Reentrancy can be maintained by a module that updates itself so
long as the update is properly serialized.
I discovered the 'hard way' just how many RENT modules from IBM update
themselves while executing in PSW key zero. Crashed our systems numerous times
back in the OS/390 days (before REFRPROT) using the CSVRENTSP252 DIAG TRAP. Each
time had to add a module name to an exception table in the nucleus, re-link and
re-IPL. It was ugly...
--
Edward E Jaffe
Phoenix Software International, Inc
831 Parkview Drive North
El Segundo, CA 90245
310-338-0400 x318
[email protected]
http://www.phoenixsoftware.com/
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