Sender ERP
The SNA CANCEL request can be used during
sender error recovery processing as necessary to terminate the chain
in error and to provide synchronization between half sessions. CANCEL can
be either solicited (by the sender of the exception response) or unsolicited
(because of a receiver-detected error, which results in an exception
response).
If necessary during chain RU or autopaged output, the
sender of the exception response enters into an ERP PURGE mode until
both half sessions' send/receive states are again synchronized. The receiver of the exception response
must cause the resynchronizing event. This event can be one of the
following:
- An RQD1 or RQD2
- Receipt of change-direction
- A
CANCELrequest (caused by either RQD1 or RQE1/CD), if the exception response occurs during an output chain - A
CHASErequest (because of RQD1 on CHASE), if the exception response is received while IMS is between RQE1 output chains (pages) of an autopaged output message
Related reading: For more information on sender error recovery procedure (ERP), see z/OS® Communications Server: SNA Programming.