General facts about C to PL/I ILC

ILC between C and Enterprise PL/I for z/OS® is discussed in the IBM Enterprise PL/I for z/OS library.
PL/I routines can run in non-Initial Process Threads (non-IPTs) created by the C routines in z/OS UNIX-conforming C to PL/I applications.
PL/I Multitasking Facility (MTF) does not support C.
With Enterprise PL/I for z/OS, a C program that is fetched from a PL/I main must be compiled with the most recent C compiler. If another version of C is desired, specify OPTIONS(ASM).
Language Environment does not support passing return codes between PL/I and C routines in an ILC application.
A C NULL is X'00000000'; a PL/I NULL is X'FF000000'; a PL/I SYSNULL is X'00000000'. Comparisons against a NULL value and other uses of the NULL value must therefore be done with care.
There is no ILC support between AMODE 31 and AMODE 64 applications. PL/I does not support AMODE 64.