At 9:39 AM -0500 on 07/06/2010, Paul Gilmartin wrote about Re: ENQ
trap for dynamic allocation:
(Three) scarcely helps. RACF does not intervene against ENQs. If a
job contains "//N DD DISP=OLD,DSN=SYS1.LINKLIB", JES2 will bring it to
an initiator where it will wait until all other ENQs of SYS1.LINKLIB
are freed.
This need to wait brings up one of my Hot Button design flaws with
ENQ. There is no way for an Exclusive ENQ to be converted to a Shared
ENQ. Due to this design flaw, a multi-step job that has DISP=OLD in
step 1 and DISP=SHR in subsequent steps owns an exclusive ENQ until
the last step ends instead of having the subsequent steps having a
Shared ENQ once step 1 ends (and allowing other DISP=SHR jobs to
run). Since I own the EXC ENQ and there is a queue of SHR ENQs
waiting for me to release the EXC ENQ, I see no reason why the EXC
entry can not be altered to a SHR and to then drive the code to run
the queue to release the holds on the SHR requests until a queued EXC
request is encountered.
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