1. A method for managing mainframe computer system usage comprising: implementing a management system controller on one of a plurality of logical partitions executed by a mainframe computer system; implementing a management system agent on each of the plurality of logical partitions; receiving a first performance optimization goal for workload performance in a first service class, the first service class having a first defined performance goal; assessing achievement of the first performance optimization goal; determining a first preferred value for the first defined performance goal based on assessing achievement of the first performance optimization goal; performing at least one of: a) requesting to change the first defined performance goal to match the first preferred value; receiving an affirmative response to the request to change the first defined performance goal; and changing the first defined performance goal to match the first preferred value; and b) automatically changing the first defined performance goal to match the first preferred value when the first preferred value is different therefrom; wherein workload tasks are subsequently managed in the first service class according to the changed first defined performance goal.