PoolLimitSQLException

I'm using weblogic 10.3.5.  My current configurations are the default ones

Initial Capacity: 1

Maximum Capacity: 15

Capacity Increment: 1

I got the below errors.  I have a process that will query a database every minute using JDBC in java.  This is the only process that will access this database.   In my code I close the connections already once I'm done with it.

Right now I increased the Maximum Capacity to 150.  My question is what is the appropriate pool size that I should put in? Thanks

weblogic.jdbc.extensions.PoolLimitSQLException: weblogic.common.resourcepool.ResourceLimitException: No resources currently available in pool VentasCnn to allocate to applications, please increase the size of the pool and retry..