there are four optional parameters to configure your connection pool. min-pool-size (default: 0 = none) max-pool-sie (default:20) idle-timeout-minutes(default:0 = infinite) blocking-timeout-millis(default=5000) if you have high peek concurrency, you can try setting the timeout to a reasonable timing. max-size is hardcapped - you cannot get over this value at any rate. actually, the pool behaviour ( - which pool is chosen) depends on your xml-datasource configuration: http://wiki.jboss.org/wiki/Wiki.jsp?page=JBossJCAPooling View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4027449#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...