When you define a PC routine, you define its operating characteristics and its environment. Several definitions apply to both basic and stacking PC routines. Other definitions apply to stacking PC routines only.

For each PC routine, you must specify the type of linkage, basic or stacking, that the system is to use when a user invokes the routine. IBM® recommends that you use only the stacking linkage. To define the type of linkage, use the PC keyword on the ETDEF macro.

All of the information that you provide to define a basic PC routine you also provide to define a stacking PC routine. There is also additional information that you can provide for stacking PC routines only. The topic Definitions common to both stacking and basic PC routines explains how to provide the definitions common to both types of PC routines. The topic Definitions for stacking PC routines only explains how to provide the definitions that apply to stacking PC routines only.