Rational Developer for System z
PL/I for Windows, Version 8.0, Programming Guide

STDCALL linkage (Windows only)

To use this linkage convention, you must specify the OPTIONS(LINKAGE(STDCALL)) attribute in the declaration of the function, or specify the DEFAULT(LINKAGE(STDCALL)) compile-time option.

Rational Developer for System z
PL/I for Windows, Version 8.0, Programming Guide