CAIRIM failed to load the CA Datacom PC routines resulting in DB90155E error although CA Common Services CAMASTER has been installed.
The originating problem was that CAMASTER initialization failed at IPL. This was because the linklist had a mix of CA Common Services release libraries.
Once the latest/current CA Common Services CAW0LINK library preceded all others, the problem was resolved.
See the following article for more information...
TEC592121 The CAMASTER address space initialization will fail after issuing a CAMS321E message during an IPL
Additional articles on CAMASTER and CA Datacom are...
TEC601882 Is CAMASTER Really Required for CA Datacom to Work?
TEC580882 Load of PC routines via CAIRIM fails due to DB90155E error