ADM1823E active log file full

I found this message in the db2diag.log :

ADM1823E  The active log is full and is held by application handle
  "371".  Terminate this application by COMMIT, ROLLBACK or FORCE
  APPLICATION.

Doing some research there were a couple of potential causes

1.Potentially long running query - not commiting i.e database configured to run 12 log files on a circular.
If the transaction has not been commited and you go through the 12 log files - then try to write to log file 1 again - which is still holding the open transaction, then you've got a problem. This is one possible reason , and requires further investigation
2.Known problem of DB2 Health Monitor coming on every 2 hrs - despite having it turned off - requires Environment variable changes,more details below. This has already been dealth with via the DB2_FMP_COMM_HEAPSZ=0

The actual resolution of the problem : The problem reappeared after 2 hrs : Did the following:

db2 get snapshot for applications on MONITOR

and look for application handle "371".

This showed that the last handles was in Lock-wait state , and the application was DB2HMON
I then released the lock db2 " force application ( 371 ) "

On this basis I discovered a current major issue with DB2 - regarading DB2 Health Monitor and OLTP dbs . Even if you have the Health Monitor turned OFF ,
every 2 hrs the Health Monitor will start and check everything is OK - run some maintenance etc - at this point there is a lot locking etc

I issued the following commands - see Appendix 1 on every instance on the server - and did a full restart. Note : the following changes are environment variables

db2 update dbm cfg using HEALTH_MON OFF
db2set DB2_FMP_COMM_HEAPSZ=0

 Ref:Jack Vamvas(http://www.dba-db2.com)