First, thx for your response. I planned to use it only to manage in-memory locks but I realized after that I don't need a transaction manager to do that. As a confirmation, I have read here http://www.jboss.com/index.html?module=bb&op=viewtopic&t=138918 your message : anonymous wrote : Isolation level applies to in-memory locking as well so it is relevant even if you are not using a TM. do this mean this attribute : <attribute name="IsolationLevel">READ_COMMITTED</attribute> | would be taken into consideration by jboss cache for in memory cache even if there is no transaction manager ? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4164227#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...