Conversation queues for macroinstruction processing

Conversation queues are used to store macroinstructions until their processing is complete. A conversation queue, in general, is used to store macroinstructions that perform a specific function. For example, a macroinstruction that sends expedited information is stored on the EXPEDITED SEND conversation queue until processing of the macroinstruction is complete.

VTAM® limits the conversation queues to a maximum of one macroinstruction outstanding on a conversation queue at a time. If an APPCCMD macroinstruction is issued when that queue is at its limit (that is, a macroinstruction is already being held), it is rejected with an RCPRI, RCSEC combination of X'002C', X'0011', PARAMETER_ERROR— PREVIOUS_MACROINSTRUCTION_OUTSTANDING. The following macroinstructions are exceptions and may be allowed to process if there is a macroinstruction already outstanding on the queue:

APPCCMD CONTROL=DEALLOC|DEALLOCQ, QUALIFY=ABNDPROG
APPCCMD CONTROL=DEALLOC|DEALLOCQ, QUALIFY=ABNDSERV
APPCCMD CONTROL=DEALLOC|DEALLOCQ, QUALIFY=ABNDTIME
APPCCMD CONTROL=DEALLOC|DEALLOCQ, QUALIFY=ABNDUSER
APPCCMD CONTROL=REJECT, QUALIFY=CONV

VTAM also allows only one APPCCMD CONTROL=TESTSTAT, QUALIFY=ALL|IALL to be outstanding at a time. If one of these macroinstructions is outstanding, the issuance of another one will be rejected with an RCPRI, RCSEC combination of X'002C', X'0011', PARAMETER_ERROR—PREVIOUS_MACROINSTRUCTION_OUTSTANDING.

The following macroinstructions are queue-independent; their acceptance is not related to a particular existing conversation:

APPCCMD CONTROL=ALLOC
APPCCMD CONTROL=CHECK
APPCCMD CONTROL=OPRCNTL
APPCCMD CONTROL=PREALLOC
APPCCMD CONTROL=RCVFMH5, QUALIFY=NULL|QUEUE
APPCCMD CONTROL=REJECT, QUALIFY=SESSION
APPCCMD CONTROL=REJECT, QUALIFY=CONVGRP
APPCCMD CONTROL=SETSESS

The APPCCMD CONTROL=RCVFMH5, QUALIFY=DATAQUE macroinstruction is initially queue-independent but moves to the SEND/RECEIVE queue for the receive function.

VTAM has no limit to the number of APPCCMD CONTROL=ALLOC|PREALLOC macroinstructions an application program can issue.

At certain points during conversation deallocation, VTAM prohibits further macroinstructions from being accepted for the conversation queues. The application program will then receive an RCPRI, RCSEC combination of X'00A0', X'0002', REQUEST_NOT_ALLOWED— REQUEST_BLOCKED, on any macroinstruction issued that is directed to one of the conversation queues. This return code indicates that the conversation is in the process of being deallocated or terminated and no other processing will be accepted for the conversation.