There's a "gotcha" that you have to remember ...
If you allocate a data set, ignoring existing allocations, then if the new allocation is exclusive and the old allocation was share, the old enqueue will be promoted to exclusive. Then when you FREE the newly allocated data set the exclusive enqueue will NOT be released until the original allocation is free'd.
DanD -------------------------------------------------- From: "Thomas Berg" Subject: SV: About ENQ - some basic questions
Thanks! It was as I suspected, more or less. Regards, Thomas Berg __________________________________________ Thomas Berg Specialist IT-U SWEDBANK-----Ursprungligt meddelande----- Shmuel Metz (Seymour J.) Ämne: Re: About ENQ - some basic questions on 02/09/2010 at 04:49 PM, Thomas Berg said: >As I'm playing a bit with an ENQ-function, I wonder how ENQ's work when >doing dynamic allocation. The same as any other ENQ or RESERVE, except that you're not the one issuing it. >Normally - as I understand - an ENQ is always released when the >(sub)task terminates (or doing DEQ). An ENQ is release when the task owning the resource terminates. For an unprivileged caller, that's the task issuing the ENQ. DYNALLOC is a privileged caller, so it is more complicated. >But if You e g do an allocation in the same rexx its ENQ is kept thru >the entire TSO session or until You free the dataset. More or less, except that an allocation might be marked not in use, which is sort of intermediate between allocated and unallocated. >Does this mean that the ENQ in this case is assigned to the main task >(TSO) or is there another mechanism in work ? The ENQ is assigned to the Initiator task for the jobstep; that's the login task for foreground TSO. -- Shmuel (Seymour J.) Metz, SysProg and JOAT
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