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Quasi re-entrant in CICS.
Posted: Fri Jul 29, 2016 5:12 pm
by Chandar Bhan
Hi,
There is a concept of Quasi re-entrant in CICS. Is there a seeting we need to do to make a program a quasi retentrant? How do we tell CICS that a program is Quasi reentrant?
Thanks,
Re: Quasi re-entrant in CICS.
Posted: Fri Jul 29, 2016 6:19 pm
by Robert Sample
Google is your friend. Googling
quasi reentrant returns about 61,200 hits and one of them is
https://www.ibm.com/support/knowledgece ... irent.html which has (emphasis added by me)
CICS runs user programs under a CICS-managed task control block (TCB). If your programs are defined as quasi-reentrant (on the CONCURRENCY attribute of the program resource definition), CICS always invokes them under the CICS quasi-reentrant (QR TCB). The requirements for a quasi-reentrant program in a multithreading context are less stringent than if the program were to run concurrently on multiple TCBs.
CICS requires that an application program is reentrant so that it guarantees consistent conditions. In practice, an application program might not be truly reentrant; CICS expects "quasi-reentrancy".
For example, application programs could modify their executable code, or the variables defined within the program storage, but these changes must be undone, or the code and variables reinitialized, before there is any possibility of the task losing control and another task running the same program.
Re: Quasi re-entrant in CICS.
Posted: Mon Oct 17, 2022 1:23 pm
by Chandar Bhan
Thanks Robert.
These changes are at system level but as a programmer that means we don't really need to make specific changes or do we?