Programming guidelines

z/OS DFSMStvs Administration Guide

Programming guidelines

z/OS DFSMStvs Administration Guide
GC52-1388-00

Usually, you should observe these guidelines in coding a routine:

Code your routine reentrant
Save and restore registers (see individual routines for other requirements)
Be aware of registers used by the VSAM request macros
Be aware of the addressing mode (24 bit or 31 bit) in which your exit routine will receive control
Determine if VSAM or your program should load the exit routine.