Purpose of this information: This information presents the information you need to write REXX programs that access z/OS UNIX System Services (z/OS UNIX). It describes the features and usage requirements for the z/OS UNIX REXX extensions, or syscall commands, which are interfaces between the z/OS operating system and the functions specified in the POSIX.1 standard (ISO/IEC 9945-1:1990[E] IEEE Std 1003.1-1990: First edition 1990-12-07; Information technology—Portable Operating System Interface [POSIX] Part 1; System Application Program Interface [API] [C Language]). These functions are used by z/OS UNIX. This document also describes syscall commands that are not related to the standards.

Who should read this information? Programmers who are already familiar with the REXX language and experienced with the workings of TSO/E and z/OS UNIX should read this information. They will learn how to include in a REXX program syscall commands that access z/OS UNIX services.