how to use different overflow files for the Sentinel connector?

when this configuration is not done errors like below can be seen in the trace viewer:
-ERROR 20100709 12.49.16.55 procengine(procengine(hierchmsgenv))
[STX - 25011]: Unable to open STL : setSendFile returned -21
-DEBUG 20100709 12.49.16.55 procengine(procengine(hierchmsgenv))
[STL - 1]: The overflow file name is /XIP_01/data/sentinel/mc_overflow for this procengine (PID=936). This file must not be used by several procengines.
-DEBUG 20100709 12.49.16.55 procengine(procengine(hierchmsgenv))
[MON - 1001]: Failure while executing MapStage (DE01.EAI\RBEE_IOrperEmet.IT_RBEE_IBEE_Piv.GenPivot)
-DEBUG 20100709 12.49.16.55 procengine(procengine(hierchmsgenv))
Session finished with error

when several procengines are used by the HME, the use of an overflow file in the sentinel connector failed. A concurrent access corrupts the mechanism. The overflow file name can be set thanks to an environment variable "SENTINEL_OVERFLOWFILE". If this variable is not set the overflow file will be as previously CORE_DATA/sentinel/mc_overflow.
This must be set for each procengine in $CORE_LOCAL/config/environment.dat