Selecting a Compatible Activation Group
Selecting a Compatible Activation Group
An activation group reflects the storage model of the root program that caused the activation group to be created. The storage model determines the type of automatic, static, and constant storage that is provided to the program.
Single-level storage model programs receive single-level automatic, static, and constant storage. By default, these programs will also use single-level storage for heap storage.
Teraspace storage model programs receive teraspace automatic, static, and constant storage. By default, these programs will also use teraspace for heap storage.
Programs that use the teraspace storage model cannot be activated into an activation group whose root program uses the single-level storage model (this includes the OPM default activation groups). Programs that use the single-level storage model cannot be activated into an activation group whose root program uses the teraspace storage model.
The following table summarizes the relationship between storage models and the activation group type.
Table 1. Relationship of storage models to activation groups
| Program storage model | Activation group attribute | |||
|---|---|---|---|---|
| *CALLER | *DFTACTGRP | *NEW | Named | |
| *TERASPACE | Yes | Not allowed. | Yes | Yes |
| *INHERIT | Yes | Not allowed. | Not allowed. | Not allowed. |
| *SNGLVL | Yes | Yes | Yes | Yes |
When you choose the activation group in which your program or service program runs, consider the following guidelines:
- If your service program specifies STGMDL(*INHERIT), you must specify ACTGRP(*CALLER).
- If your program specifies STGMDL(*TERASPACE):
- Specify ACTGRP(*NEW) or a named activation group.
- Specify ACTGRP(*CALLER) only if you can assure that every program that calls your program uses the teraspace storage model.