The message "Gen check completed" started to appear once per day in CICS MSGUSR log after a recent Gen 8.6 PTF update for TIRORUNC.
Gen 8.6 runtime applications for CICS
The daily message is due to new SCRT reporting enhancements delivered in recent PTFs.
For further details please see Gen 8.6 doc page Gen Licensing and section "Mainframe LMP License Keys":
z/OS CICS Runtime SCRT Update
After applying this PTF LU14059, usage of Gen CICS Runtime is reported on the SCRT report.
There is one check done once per day for the CICS region wherever Gen applications are executed.
Since the LMP code 4A is removed from Construction in PTF LU13160, now it is reported for CICS runtime usage.
If Common Components and Services PTF LU13705 is also applied the correct product name is reflected in the SCRT report.
Gen EDGE Community post: New message after Gen maintenance applied for TIRORUNC