Using MFS with ISC
Message formatting for MFS DPM is specified on the IMS system definition TERMINAL macro statement by the parameter DPM-Xn, where X might be A or B. For ISC nodes, the form DPM-Bn is always used.
- How MFS DPM-Bn can be invoked to format IMS input and output
- The way in which the ATTACH, SCHEDULER, and reset attached process (RAP) function management headers are used by MFS
- MFS support for the SNA-defined QMODEL and data descriptor function management headers (which control MFS processing)
Some input MFS format errors (such as invalid cursor, incorrect output formats, or no output formats) are not detectable within IMS before IMS sends the requested response to the input message. In these cases, IMS sends the error message by using ATTACH ATTDPN=SYSMSG. This ATTACH results even if the input message indicated change-direction and exception response and is an implicit acknowledgment to the message.
An ATTACH SYSMSG received by IMS during demand-paged output is treated as an invalid MFS paging request and causes session termination. The received SYSMSG is discarded.