At 18:40 -0400 on 07/30/2006, Bruce Black wrote about Re: Data set
ENQueues and DEQueues in Jobs:
I have the impression that the initiator is also smart enough to issue
a ENQ TYPE=CHNG (to switch from ENQ=EXC to ENQ=SHR) if subsequent
steps have the DSN as DISP=SHR after the last step that has it as
DISP=OLD (ie: Exclusive).
Sorry, ENQ RET=CHNG only changes a SHR ENQ to EXCL, not the other waqy
My error. I remembered that the ENQ had the ability to change the ENQ
type but forgot that it was from SHARED to EXCLUSIVE (which is not as
useful as from EXCLUSIVE to SHARED - if there is some purpose in
allowing S->E, it should be in addition to not in lieu of E->S). In
fact, I can not think of any situation where you'd want to be able to
gain EXCLUSIVE access after having SHARED Access while (as I noted)
having EXCLUSIVE access and switching to SHARED (so others can have
SHARED access before you terminate and totally give up the ENQ) seems
more useful (such as being able to have DISP=SHR access in a Job
Stream where only Initial Steps needs to have DISP=OLD). Right now,
once you gain DISP=OLD in a Job Step, you keep it in subsequent
DISP=SHR steps due to the bad design of ENQ that refuses to allow you
to "relax" your ENQ while still maintaining it.
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