Modify the assembler driver

If the assembler driver uses either IGZERRE or ILBOSTP0, it must be modified.

Replace the OS/VS COBOL ILBOSTP0 or IGZERRE 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 was not available with OS/VS COBOL.