Resolution:
Check the log file for the complete stack trace, if it resembles the one like below, then it means the process is running out of descriptors. The quick way to solve this problem is to try with a lower connection pool size

Stack Trace
---------------
2007 Nov 13 17:28:50:145 GMT -8 msubrama-lt.na.tibco.com User [main] - Initializing BECoherenceOracleStore for cache BACME-FraudDetection.be.gen.Concepts.Account forcedInit=true
2007 Nov 13 17:28:50:435 GMT -8 msubrama-lt.na.tibco.com Error [main] - java.sql.SQLException: Listener refused the connection with the following error:
ORA-12519, TNS:no appropriate service handler found The Connection descriptor used by the client was:
localhost:1521:XE

2007 Nov 13 17:28:50:435 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:112)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:261)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:387)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.driver.PhysicalConnection.&ltinit>(PhysicalConnection.java:414)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.driver.T4CConnection.&ltinit>(T4CConnection.java:165)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:35)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:801)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.pool.OracleDataSource.getPhysicalConnection(OracleDataSource.java:297)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:221)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at oracle.jdbc.pool.OracleDataSource.getConnection(OracleDataSource.java:165)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at com.tibco.be.oracle.impl.OracleConnectionCache.createConnections(OracleConnectionCache.java:31)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at com.tibco.be.oracle.impl.OracleConnectionCache.registerConnection(OracleConnectionCache.java:79)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at com.tibco.be.oracle.BECoherenceOracleStore.registerOracleDataSource(BECoherenceOracleStore.java:151)
2007 Nov 13 17:28:50:445 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at com.tibco.be.oracle.BECoherenceOracleStore.registerOracleDataSource(BECoherenceOracleStore.java:138)
2007 Nov 13 17:28:50:455 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at com.tibco.be.oracle.BECoherenceOracleStore.initialize(BECoherenceOracleStore.java:221)
2007 Nov 13 17:28:50:455 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at com.tibco.be.oracle.BECoherenceOracleStore.&ltinit>(BECoherenceOracleStore.java:96)
2007 Nov 13 17:28:50:455 GMT -8 msubrama-lt.na.tibco.com Error [main] -     at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)