Using System Macro Instructions

This information covers system macro instructions. The macros are grouped functionally where appropriate and perform the stated functions.

Ensure data security (DEBCHK macro)
Obtain device characteristics from control blocks and system tables (DEVTYPE macro)
Modify the JFCB (RDJFCB and OPEN TYPE=J macros)
Manipulate I/O activity queues (PURGE and RESTORE macros)
Perform track capacity calculations (TRKCALC macro).
Perform calculations and conversions with 28-bit cylinder addresses (TRKADDR macro).

Some functions of these macros tend to depend on the internal logic of the system.

Before reading this information, you should be familiar with the publications High Level Assembler/MVS & VM & VSE Language Reference They contain the information necessary to code programs in the assembler language.