Actuators based on dielectric electroactive polymers (DEAP) use the electrostatic pressure to convert electrical into mechanical energy. Stack-actuators are a common approach to realize DEAP-based multilayer actuators. To optimize the stationary generated force and stretch the influences of material and free design parameters are investigated based on a model of a loss-free actuator. For this purpose the stretch-force-behavior depending on the applied electric energy is introduced. Based on this approach, besides the general scalability of the force and stretch, an optimal operating point can be determined at which the ratio of generated mechanical work to the applied electrical energy is maximized. To further consider performance limitations of such actuators the known effect of electromechanical instability is finally investigated depending on the generated force yielding to critical stretches, forces and energies.