DRCP num_cbrok configuration

Oracle RDBMS EE 12.2.0.1

Using DRCP.

How to setup num_cbrok with higher values than default=1?

I can get information regarding the POOL using the following query:

select*from DBA_CPOOL_INFO; shows num_cbrok = 1 

I cannot find NUM_CBROK parameter while reading the documentation for DBMS_CONNECTION_POOL.ALTER_PARAM and DBMS_CONNECTION_POOL.configure_pool.

It seems that such parameter is not available for configuration.

Executing the following gets error messages:

exec dbms_connection_pool.configure_pool (num_cbrok=>16);

exec DBMS_CONNECTION_POOL.ALTER_PARAM (num_cbrok=>16);

Error messages are as follows:

PLS-00306: wrong number or types of arguments in call to 'ALTER_PARAM'