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

Invoking PL/I routines from a non-PL/I main

The PL/I run-time environment has the ability to:

A PL/I routine invoked from a non-PL/I routine should handle any exceptions that occur in PL/I code and returns to the non-PL/I using a RETURN or END statement in the first PL/I procedure (see Using ON ANYCONDITION)

The PL/I run-time implicitly frees any resources acquired by PL/I, but not until the application terminates.

You can also explicitly resources through various PL/I statements:

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