If you want to modify the assembler driver routine, you can replace the OS/VS COBOL ILBOSTP0 routine with the Language Environment CEEPIPI INIT_SUB, CEEPIPI INIT_ MAIN, and CEEPIPI TERM functions. These Language Environment routines have a convenient complementary termination function that is not available with OS/VS COBOL.
If either IGZERRE or ILBOSTP0 is statically linked with the assembler driver, the assembler driver must be link-edited with Language Environment. If ILBOSTP0 is used, you must specify the Language Environment options ALL31(OFF) and STACK(,,BELOW).
For alternative methods to use preinitialization, see Initializing the runtime environment.