Prior to V5R3 the miximum size of a *USRQ was 32MB less some overhead for
queue definition information.  In V5R3 the limit was increased to 2GB (less
some overhead for queue definition).

Bruce Vining

             Dave McKenzie                                                 
   >                                                     To 
             Sent by:                  MI Programming on the AS400 /       
             mi400-bounces@mid         iSeries <mi400@xxxxxxxxxxxx>        
             12/20/2005 11:03          Re: [MI400] Refresh my memory: is   
             AM                        there some sort of  unstructured    
                                       object that's cheap to create, and  
                                       can automatically   expand?         
             Please respond to                                             
             MI Programming on                                             
                the AS400 /                                                

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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