Bytes Available not correct in API QMHRTVM

[Dave Murvin <davem@xxxxxxxx>]

I am trying to use the RTVM0400 format of the QMHRTVM (Retrieve message) 
API and am not getting the expected results in the returned Bytes Available 
field (second field in the RTVM0400 format - field QMHBAVL14 in the QSYSINC 
copy file).  Sequence of events is:

1. Allocate 8 bytes to the Message information input parm so I can get the 
first two fields in the RTVM0400 format and find out how big the message 
information is.
2. Call QMHRTVM for my particular message passing 8 in the Length of 
message info input parm.
3. RTVM0400 Bytes available field is 328
4. reallocate Message information input parm to hold 328 bytes
5. Call QMHRTVM again, passing new length available as 328 bytes (Length of 
message information input parm)
5. RVTM0400 Bytes available field is now 684 bytes!  Bytes actually 
returned returned is 328 as expected.

The problem is that, as I understand the APIs,  the first call to QMHRTVM 
should have returned 684 bytes in the Bytes Available field.

If I call QMHRTVM and allocate 3000 bytes on the first call, it does return 
the correct 684 bytes, but this does not seem to be the way it should work.

I didn't see anything in the archives or on the IBM APAR site.

I am at V5R3.

Any suggestions?

Thanks


Dave Murvin
DRM Enterprises, Inc.