To include MFS input message segment and field exits in IMS applications, follow these coding standards:
- Write all input message segment and field exits in COBOL. This is different from IMS/ESA, where segment and field exits are written in Assembler.
- Use the IMS/ESA naming convention as follows:
DFSMEnnn
Where
nnn is the exit number expressed as a three-digit decimal number from 000 through 127. For example, for field exit number
zero, use the name
DFSME000.
- Segment and field exits receive ASCII data. If the exit program is written for EBCDIC, it must also convert the IMS data it receives in ASCII from ASCII into EBCDIC, and convert the data from EBCDIC back to ASCII before exiting.
- Be sure that segments are not modified such that they are rendered invalid. Invalid segments can cause runtime errors.
- Do not use an exit to invoke IMS callable services, including storage services and control block services.
Note: If an MFS source references an exit that does not exist, the program behaves as if there were no exit coded in the MFS. Exception conditions returned by the exit are written to the server console log.
