I've used *USRQ's in QTEMP, and the only "gotcha" I remember was that *USRQ's are limited in size to about 24 MB. That shouldn't normallly be a problem, but in our application, we could exceed 24 MB on vary rare occasions. We had to build homemade queues out of multiple *USRSPC's (and a *USRIDX if it required keys).

The 24 MB number seems very strange. Usually objects are limited to some multiple of 16 MB (the size of a segment group). E.g. *USRSPC's are limited to 16 MB because they are designed to consist of just one segment group.

I never dug in deep enough to find why the 24 MB limit.


James H H Lampert wrote:
Dave McKenzie <davemck@xxxxxxxxxxxxx> wrote:
Since you mentioned FIFO access, you may also be thinking of a User Queue, which you can create with the QUSCRTUQ API, and access with ENQ and DEQ/DEQWAIT instructions (in MI or C).

Thanks. I'd forgotten the somewhat convoluted way in which *USRSPCs can be made self-expansile, and I've never used a *USRQ.

Are there any known V5 "gotchas" regarding *USRQs in QTEMP?


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