Using the LAST option

The LAST option on the SEND command indicates the end of the conversation. No further data flows can occur on the session, and the next action must be to free the session. However, the session can still carry CICS® syncpointing flows before it is freed, provided the LAST request has not been flushed.

A syncpoint, whether on an APPC or MRO session, is initiated explicitly by a SYNCPOINT command, or implicitly by a RETURN command. However, the circumstances under which session syncpointing occurs, and the ways in which syncpointing can be avoided on the session, differ for APPC and MRO.

The LAST option and syncpoint flows on APPC sessions

If an APPC mapped conversation has been terminated by a SEND LAST command, without the WAIT option, transmission will have been deferred, and the syncpointing activity causes the final transmission to occur with an added syncpoint request. The conversation is thus automatically involved in the syncpoint.

If the conversation is not to be involved in the syncpoint (for example, because the partner transaction does not access any recoverable resources), the transaction must issue a SEND LAST WAIT command, or a FREE command, to force the transmission before using a command that causes a syncpoint.

The LAST option and syncpoint flows on MRO sessions

If an MRO conversation is terminated by a SEND LAST command, without the WAIT option, the WAIT implicit in all MRO commands is applied, and the data is transmitted. However, in anticipation of subsequent syncpoint flows, CICS does not send the LAST indicator with this data.

If the conversation is not to be involved in the syncpoint (for example, because the partner transaction does not access any recoverable resources) you must specify the WAIT option explicitly on the SEND LAST command to force the LAST indicator to be sent with the data. Alternatively, you could follow the SEND LAST command by a FREE command.

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