1. A method for managing mainframe computer system usage comprising: implementing a plurality of logical partitions on the mainframe computer system, each of the plurality of logical partitions executing a plurality of workload tasks in a plurality of service classes, one of the plurality of logical partitions executing a management system controller and each of the plurality of logical partitions executing a management system agent; receiving a first performance optimization goal for performance of the plurality of workload tasks in a first service class of the plurality of services classes, 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; generating a first notification including the first preferred value; changing the first defined performance goal to match the first preferred value; and managing performance of the plurality of workload tasks in the first service class of the first logical partition according to the changed first defined performance goal; wherein the first performance optimization goal is determined using at least one separate performance parameter that is not a performance parameter of the first defined performance goal; wherein the first service class includes first and second service class periods, the first defined performance goal including separate first defined performance goals for the first and second service class periods; wherein receiving the first performance optimization goal for workload performance in the first service class includes receiving separate first performance optimization goals for the first and second service class periods; wherein assessing achievement of the first performance optimization goal includes assessing achievement of the separate first performance optimization goals for the first and second service class periods, respectively; and wherein determining the first preferred value includes determining separate first preferred values for the first and second service class periods based upon the respective achievement assessments.