Do not use ActiveCount to get sure if the connections are being released or not, use the AvailableConnections.
ActiveCount takes into account connections that were released but are still in a idle state in the pool. If your AvailableConnections never increase after using connections, so you can start to be worried.
where i can find this value? in console Available is the pool max value, and not change.
no, that value is the max-pool-size (30) and not change....now I have available 30,active 3 and max used 3
If the value of Available is 30, and you've configured the maximum of your pool as 30, you are in the best scenario, none connections are stucked. I don't see your worry.
my worry is that i noticed after some times (one week i don't know) that active and max used goes to 30 without any apparent reason...and not goes down. The load is quite small so almost impossibile that application needs 30 connections.
I have another data source where actice is 1 and max is 2, so connections are released well. In first data source i've never seen active count less than max used, and it's very strange. yesterday i restarted jboss to enable jca logging, so connection count was reset.
Again, the the scenario of ActiveCount=30 does not means trouble!! The trouble would be AvailableConnection=0. You are considering the wrong parameter.
An active connection is not necessarily in use, but also could be in a idle state, waiting to be taken in the pool. Look at the definition in 
The number of active connections. Each of the connections is either in use by an application or available in the pool
See, "or available in the pool", it means that not necesseraly the connection in this state is unavailable for the application.