Dear PotterMan:
Welcome back. You did not say what application server this is for. My guess is JBOSS. If so , this will help answer your question. Check teh JBOSS docs then for further info.
https://communities.ca.com/thread/241722807
https://www.safaribooksonline.com/library/view/jboss-a-developers/0596100078/ch04s05.html
You might occasionally want to adjust the pool size to account for usage; you are more likely to be curious how much of the connection pool is being used. The ConnectionCount attribute shows how many connections are currently open to the database. However, open connections are not necessarily in use by application code. The InUseConnectionCount attribute shows how many of the open connections are in use. Viewing the statistic from the other direction, AvailableConnectionCount shows how much room is left in the pool.
Please let me know if this is helpful and mark as correct if it answers the question
Thanks
Hal German