Connections are resources that the application uses and a fewer connections can be used by multiple threads if the threads are not always busy with the database activity only, and are doing other work too. This sharing (pooling) can be implemented by the application or the application can leverage the connection pooling features offered by OCI/OCCI (recommended).
Be aware of connections vs sessions and sharing them (refer to :
OCCIConnectionPool is to pool connections and OCCIStatelessConnectionPool is to pool sessions. Please see the differences in the above link and apply as appropriate.