When a batch job uses services of an IDMS Central Version, it works like
this:
The batch job makes a request of the IDMS central version (used to be via
an SVC), then waits.
The IDMS central version processes the request - at the IDMS CV's
dispatching priority. When the request finishes, CV posts the batch job.
The ENQ is how the IDMS Central Version recognizes when a batch run unit
"goes away" without committing. The batch job latches onto an ENQ before
it issues an IDMS "BIND" call. As part of its BIND processing, the
Central Version attempts to ENQ on the same resource name. If CV (the
central version) actually gets control of the ENQ, it knows that the batch
run unit went away without saying goodbye ("COMMIT"), so it initiates a
rollback.
Makes life interesting.
Ancient Chinese curse: "may you live in interesting times".
Tom Puddicombe
Mainframe Performance & Capacity Planning
CSC North American Public Sector - Civil Group
Computer Sciences Corporation
Registered Office: 3170 Fairview Park Drive, Falls Church, Virginia 22042,
USA
Registered in Nevada, USA No: C-489-59
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Subject
IDMS batch jobs getting increased dispatching priority
Up front, I have to say that I know less than zero about IDMS and I was
hoping to keep it that way.
We have a rash of batch jobs extracting data from IDMS regions. God only
knows what they're doing but these jobs seem to have their dispatching
priority increased to FC range where their srvclass should have them in
the high C0 to low E0 range. The only enque that appears is 'IDMSCV BATxx'
(where xx is some hex characters). I was thinking that it could be ERV
trying to elimate enque contention but that doesn't seem to be the case.
This enque seems to be an IDMS mechanism to serialize batch usage.
Any thoughts?
Jack Kelly
202-502-2390 (Office)
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