Module Replaced by a Module with Fewer Imports

If a module is replaced by another module with fewer imports, the new program object or service program is always created. However, the updated program object or service program contains an isolated module if the following conditions exist:

Because of the now missing imports, one of the modules bound into a program object or service program no longer resolves any imports
That module originally came from a binding directory used on the CRTPGM or CRTSRVPGM command

Programs with isolated modules may grow significantly over time. To remove modules that no longer resolve any imports and that originally came from a binding directory, you can specify OPTION(*TRIM) when updating the objects. However, if you use this option, the exports that the modules contain are not available for future program updates.