When CICS TS started after the IPL, it produced the following message
instead of the normal message
TSS7000I CICSnn K#XYZ123 14 Mar 21 09:47 System=SYSA Toiminto=CICSzz
Release : 16.0
Component : CA Top Secret for z/OS
A TSS exit was installed.
EXIT(ON) with TSSINSTX being in the program.
Recompiled/linked the exit and The xxxxxxxx message disappeared.