I use JBOSS 6.1.0.Final . I am having the same issue,
would like to use <max-pool-size>${myapp.db.maxPoolSize}</max-pool-size> in myapp.ear/my-ds.xml ends up with maxPoolSize == 0
It works(maxPoolSize =5) when I give <max-pool-size>5</max-pool-size> in myapp.ear/my-ds.xml. I tried the suggestions that were mentioned in this forum, I don't find any success with adding to jboss-service.xml and dependency-deployers-jboss-beans.xml
Any idea on why this is not working? We have many ear files, so we like to change in a common place.