System/390(R) assembler invocation

         CALL MQXWAIT,(HCONN,WAITDESC,COMPCODE,REASON)

Declare the parameters as follows:

HCONN     DS       F  Connection handle
WAITDESC  CMQXWDA  ,  Wait descriptor
COMPCODE  DS       F  Completion code
REASON    DS       F  Reason code qualifying COMPCODE