System message process (SYSMSG) function management header
IMS uses the system message process (SYSMSG) function management header to send system messages.
System messages are appended to an ATTACH carrying DPN=SYSMSG. CICS® routes these messages to a
synchronous application when the session is allocated to that transaction
or to destination CSMT at any other time. If routed to a transaction,
that transaction is responsible for processing the SYSMSG function
management header. CICS does
not send SYSMSG, but a synchronous application program can cause a SYSMSG to
be sent by setting the appropriate process name in the BUILD
ATTACH. The application program is responsible for building
the appropriate SYSMSG FMH to be appended to the ATTACH.
SYSMSG is
sent by IMS for broadcast messages
or for the case in which a response to input has been sent, but has
had a subsequent processing error. After a response to asynchronous
input, SYSMSG is sent in lieu of the reply message.
During synchronous processing, SYSMSG is sent: - After a session restart, if the transaction in progress abends during the session outage
- During MFS output, if MFS output format blocks are not available or are not valid