WAS retarting by itself

we are using JDE E1 9.1 with Tools 9.1.4.7 and have been encountering the WebSphere server restarting by itself during business hours.  When the consultant looked at the dump logs he found:

JVMDUMP0391 Processing dump event "systhrow", detail "java/lang/OutOfMemoryError"

which we've been told is most likely due to a memory intensive interactive app (possible due to a wide open query or large grid import/export)

is there any way to find which app or user caused it?  Is there anyway to config WAS to prevent this from happening?

thanks

RC

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