Base Operating System (BOS) Runtime Services

This topic collection contains information, for experienced C programmers, about system calls, subroutines, functions, macros, and statements associated with base operating system runtime services.

The AIX® operating system is designed to support The Open Group's Single UNIX Specification Version 3 (UNIX 03) for portability of operating systems based on the UNIX operating system. Many new interfaces, and some current ones, have been added or enhanced to meet this specification. To determine the correct way to develop a UNIX 03 portable application, see The Open Group's UNIX 03 specification on The UNIX System website (