AMODE31 - Query addressing mode

General

Application area:	XS programming; see "XS programming"
Macro type:	Type O; see "O-type macros"

/390 servers offer the user a choice between a 24-bit addressing mode and a 31-bit addressing mode.
Any program being run above the 16-Mb boundary must execute in
31-bit addressing mode.

Macro description

The AMODE31 macro informs the user of the address mode settings. The information is passed by setting the 2³¹ and 2⁰ bits in the register specified. Bits 2³⁰ through 2¹ are overwritten. The bit settings listed below mean:

Bit 231	Bit 20	Addressing mode
0	0	24-bit addressing mode (NXS)
1	0	31-bit addressing mode (XS)
1	1	32-bit addressing mode (x86 servers)

No return code indicating the macro execution is transferred.

Macro format and description of operands

AMODE31

reg

reg
Register where information is entered.