A COBOL E35 exit program can be indicated through the EXEC statement PARM option (PARM='E35=COB'), the MODS control statement or the $ORTPARM DD statement.
Like any other E35 exit routine, the COBOL E35 is called each time a record is brought out of Phase 3. Communication between MFX and the COBOL exit takes place in the LINKAGE SECTION of the COBOL program. For example, records are passed to the COBOL routine in the second definition (RECORD-UP) area of the LINKAGE SECTION. No storage is reserved in the exit program because the records exist elsewhere.
If the COBOL exit routine uses any verb (EXHIBIT, DISPLAY, TRACE) which results in output to the SYSOUT DD statement, there is a potential conflict with MFX’s use of this DD statement. It is therefore recommended that you separate the output by using either MFX’s MSGDD PARM option or the COBOL compiler’s SYSx parm.