Is there any reason for STC LIDs to have SOURCE set?
Release : 16.0
Component : ACF2 for z/OS
SOURCE is added to prevent unauthorized use of STC logonids. STC can only have one source STCINRDR which is a source of the STC internal reader.
The reason to set SOURCE(STCINRDR) on STC logonid would be that it can be typically used to submit jobs from a started task with a valid SOURCE name.