A C E15 exit program is indicated by the MODS control statement.
Like any other E15 exit routine, the C E15 exit routine is called each time a record is brought into Phase 1 of a sort or Phase 3 of a copy. MFX and the C exit communicate through arguments defined in the function header. For example, records are passed to the C routine by the address presented in the second argument in the function parameter list. No storage is reserved in the exit program because the records exist elsewhere.
The C E15 exit routine can be written using either the C370 V2R1 compiler with the V2R2 C370 Library, the SAA AD/Cycle C370 V1R2 Compiler and Library or using the C/C++ for MVS/ESA V3R1.1 or higher Compiler and Library. When using the LE/370 run-time library modules, it may be necessary to account for this additional storage by adjusting the b value of the Exit-Name parameter on the MODS statement.