A non-unique user id is one that is not associated to a single owner, but instead can be used by more than one user. Processing with non-unique user ids assumes that your site is not using them.
The use of non-unique user ids has no impact on Link3270 server adapter business state file (DFHMAL2F) management in CICS® Service Flow Runtime V3.1. In addition, the Link3270 node property non-unique user ids is not used and is not required in CICS Service Flow Runtime V3.1. See Link3270 node properties.
For information on LU assignment processing for non-unique user ids using a FEPI adapter, see FEPI adapter LU assignment processing for non-unique UserIDs.
For information on Link3270 bridge facility assignment processing for non-unique user ids, see Link3270 bridge facility assignment processing for non-unique user ids.