CALL-GSS is uncommented and turned off(CALL-GSS=NO) in the Datacollector sysparms, the Datacollector is recycled after that but DB2 messages in option 4 still show up. How is that possible?
CALL-GSS=NO will stop Insight from invoking IMODs and writing to the ILOGs from REQUESTS. In other words, Insight requests can have an output destination of IMOD(xxx) or ILOG(xxx). If CALL-GSS=NO is specified, then the IMOD/ILOG function will NOT be invoked for those requests. Requests DB2CMDS (DB2 Commands) and UTILTRAC (Utilities) use the ILOG destination.
You can also define an Exception to write to the ILOG, and that is also controlled by CALL-GSS=YES|NO.
DB2 messages(option 4 from Insight Main Menu), however, are not under Insight control. This processing occurs completely under GSS. Therefore, if you use CALL-GSS=NO you should see ONLY DB2 messages. In other words, no messages from exceptions, commands, or utilities will be seen.
To stop Insight from dsiplaying the DB2 message you need to remove the definitions in the GSS Parmlib deck. You can also change the Data Collector sysparm MSSUB to some bogus value that doesn't match the GSS subsystem name (Default of ISRV). The messages would still be captured and written to the ILOGs, but you wouldn't be able to see them from option 4.