Each CA DCD scan request is submitted to IBM z/OS Workload Manager (WLM). The number of classification servers (DCDSRVR) is controlled by WLM service class. Thus, to limit the number of DCDSRVR address spaces running concurrently you would want to place the server in a lower priority service class.
For each of the CA Data Content Discovery controller and server started tasks, assign a Workload Manager (WLM) Service Class that meets or exceeds the following recommended dispatching priorities. Doing so lets WLM dispatch the workload (scan requests) at an acceptable level, improving product performance.
Details on WLM Service classes can be found in CA Data Content Discovery documentation in section "Assign the Appropriate WLM Service Classes to Handle the Workload".