The interfaces described in this section reflect what is possible for programs to do on an MVS/ESA SP system. When determining the attributes and linkage conventions for a program, analyze the program's individual interfaces and its overall interactions with other programs. This topic provides general guidelines for making these determinations.

You need to consider addressing modes, address space control (ASC) modes, and program residency when determining linkage conventions. See Interface considerations for the TSO/E service routines for brief descriptions of those considerations for the service routines and macro instructions described in this manual.

The following discussion provides a general description of ASC mode, AMODE and RMODE attributes. For a detailed description of ASC mode considerations, see z/OS MVS Programming: Extended Addressability Guide. For a detailed description of 31-bit addressing, see z/OS MVS Programming: Assembler Services Guide.