Hi,
see
http://forum.hibernate.org/viewtopic.php?t=929329&highlight=websphere+datasource)
Unfortunatley, this only applies to WAS 4 - I have not yet found this setting in WAS 5.
If you use WAS 5, I think setting the "Policy for deleting" to "FailingConnectionOnly" might also work.
You get there by choosing "Resources-JDBC Provider - {your driver} - Datasources - {your datasource} - Connection Pool
(Sorry I am using a German WAS, so the real English names may be different)
However I have not tried this yet for WAS 5, so please post your results here as an answer.
regards
Stefan