A role-based computer system has a first processor with a computer program (100) and has further processors with application systems (Sy1, Sy2, Sy3) and application services (Se). The program generates a start instruction for the further processors to execute the services by consecutively receiving a log-in identification from the user and looking up in a first assignment table (101) for a role (Ro), looking up in a second assignment table (102) to determine logical services (LSe) assigned to the role; and looking up in a second assignment table to determine a pointer (P(Sy/Se)) to the services (Se) that are assigned to the logical service. The pointer has first and second portions to identify the application system (Sy) and the application service (Se), respectively, and becomes part of the start instruction (350).