AMODE=31 indicates that a program must receive control in 31-bit addressing mode. Such a program can have the RMODE=24 or RMODE=ANY attribute, depending on its residency requirements. Regardless of the program's RMODE attribute, the residency of its input depends on the program's requirements. The program might require that some of its input reside below 16 MB in virtual storage, while other input might reside anywhere.

A program that runs exclusively in 31-bit addressing mode (AMODE=31) can do so provided it complies with the restrictions for invoking, and being invoked by, programs that run in 24-bit addressing mode (AMODE=24 or AMODE=ANY).

For more information on the AMODE=31 attribute, see z/OS MVS Programming: Assembler Services Guide.