Pooled connections idle timeout

Hi All,

I'm running JDBC 8.3-603 drivers against PG server 8.3.3. I'm using
JDBC3.0 API with connection pooling. Here my pool init code:

pool = new Jdbc3PoolingDataSource();
pool.setDataSourceName("DB");
pool.setServerName(servername);
pool.setDatabaseName(db);
pool.setUser(user);
pool.setPassword(password);
pool.setPortNumber(port);
pool.setMaxConnections(maxConn);

Connections are opened and closed via conn=pool.getConnection() /
conn.close().

I've noted that once a connection get opened since needed, it's never
really closed, application and database stay connected up to restart.
Since I'm writing a java server application, my application will
eventually stay up for a long time and spike of traffics can open a lot
of connectoins to PG that will never be released, even in low traffic time.

Is there any auto-idle-close mechanism, either client or server level?

Thanks in advance,

Daniele.