Default values are min-pool-size=0 and max-pool-size=10. These are configured in JBossManagedConnectionPool and overwritten by your *-ds.xml.
Have a look at http://www.jboss.org/wiki/Wiki.jsp?page=ConfigDataSources
Is there a way of outputting these values or seeing them ? Where is JBossManagedConnectionPool set up ?
After you start your server go to JMX-Console and apply filter jboss.jca:*. Look for ManagedConnectionPool MBean, this MBean will give you all the information about connection pool.
JBossManagedConnectionPool is java class responsible to setup the connection pool.