Sender ERP sense codes

The only sender ERP sense codes sent between two IMS subsystems are X'08130000' and X'0846xxxx'.

The valid contention sense codes received by IMS and additional operations performed are:
  • X'08130000'—Bracket reject; no RTR sent

    No ready-to-receive (RTR) condition is set. When the pseudo-wait is satisfied, the message is retransmitted from the beginning. This sense code can also be used to reject the SNA BIS command sent by IMS.

  • X'08140000'—Bracket reject; RTR sent

    The message is returned to the queue, and an RTR pending state is entered. No output is sent while IMS is between-brackets until an RTR is received. However, messages flow, subject to the bracket and send/receive protocol defined for the message type or component, when IMS is again left in an in-brackets/SEND state following receipt of change-direction.

After either of these sense codes, IMS attempts to send the output message.
IMS recognizes receipt of contention system sense code X'08130000' when assuming a primary half-session role, returns the output message to the message queue, and enters a pseudo-receive state that can be satisfied by:
  • Receiving input from the secondary half session
  • Being posted for output as a result of an IMS master terminal operator command, a message switch from another logical unit, or additional messages inserted by an IMS application program
After either of these actions, IMS attempts to send the output message.

IMS only indicates contention when assuming a secondary half-session role and receiving either input data or normal flow commands (BID and BIS) after having already initiated a bracket to the primary half session. IMS sends the X'08130000' sense code to indicate contention in these cases. The X'08140000' contention sense code is not sent by IMS.

Additional exception response sender ERP sense codes sent and received are:
  • X'08190000'—No output available

    This code is sent by IMS when assuming the primary half-session role and no output is immediately available following receipt of a ready-to-receive (RTR) indicator. IMS does not receive this sense code because IMS does not send RTR.

  • X'0846xxxx'—Selective Receiver ERP

    IMS sends and receives the SNA selective receiver ERP sense code. IMS sends this sense code when a response mode, conversational transaction, or application abnormally terminates. xxxx is a user sense field that is ignored by IMS when it is received. However, IMS does include this sense code in the message that is sent to the master terminal or to the terminal operator that was the source of the message. During output, it is normally set to the binary value of the IMS error message number that is sent as the ERP message when sending the response. However, the user sense code can be set to X'0000' as, for example, when the error, such as an application abend, occurs for a response mode or conversational transaction.

  • X'0864xxxx'—Function abort. Loop occurs upon retransmission. Sender should not resend data.

    IMS receives, but does not send, this function abort sense code. When receiving this code, IMS dequeues the associated output message (if still active) and then continues with normal input or output operations. xxxx is a user sense field ignored by IMS. An LUSTATUS - abort is sent by IMS if input is received prior to the end of an IMS MFS-paged output message.

    The function abort sense code X'0864xxxx' cannot be sent to IMS during nonlast IMS conversational output; otherwise, the output message is returned to the queue. The master terminal operator is notified and the session is terminated. When the function abort sense code X'0864xxxx' is sent following the last conversational output message, the message is dequeued and the Conversational Abnormal Termination exit routine is invoked just as occurs for /EXIT.

  • X'0865xxxx'—Function abort. Sender responsible to detect loop.

    IMS receives, but does not send, the sender ERP abort sense code. If received, this code causes IMS to return a message to the queue and close the session. IMS retransmits the message from the beginning at the next opportunity after session restart. xxxx is a user sense field ignored by IMS.

  • X'0866xxxx'—Function abort. Receiver responsible to detect loop.

    This sense code causes IMS to retransmit the message from the beginning at the next opportunity. The session is not terminated. xxxx is a user sense field ignored by IMS.

  • X'08670000'—Multichain ERP purge.

    IMS sends the multichain purge sense code at the end of ERP purging. IMS receives the multichain ERP purge sense code only after receiving an exception response to a nonfirst or nonlast page of an MFS output autopaged message. Non-MFS autopaged output and the first and last page of an MFS output autopaged message are sent requesting definite response. Exception to these SNA chains can result only in single chain purge.

Other sender ERP sense codes cause IMS to notify the master terminal operator and terminate the session.