In many environments, the initialization normally performed by z/OS® Language Environment® is replaced by special-purpose routines that are tailored to the specific requirements of the type of application. This requires replacing the initialization routine (CEESTART) normally used by z/OS XL C.
When you do not use the System Programming C Facilities, the compiler generates a CEESTART CSECT (control section) whenever a main() or fetchable function is encountered in the source file. With the NOSTART compiler option, described in the z/OS XL C/C++ User's Guide, you can suppress the generation of CEESTART for source files that contain a main() function where this is required. In a system programming C environment, you must compile using the NOSTART option. The object modules created will then be suitable for inclusion in applications that use the alternative initialization routines described in this section.