Sets the maximum number of available connections to be maintained in any one connection pool. Once the connection pool size has been reached any connection that is released to the pool will be closed instead of being added back to the pool. Setting the connection pool size has no effect on pbms_connect() or pbms_pconnect(), up to max_connections can still be opened.
Setting the connection pool size to zero has the effect of disabling pool (persistent) connections.
Lowering the connection pool size has the effect of closing as many unused connections as required until the new pool size is reached or until there are no more unused connections in the pool.