Extremum-Seeking Control (ESC) is a technique used to stabilize systems to optimal operating conditions. The adjustment of the controller parameters is not usually reported. In this paper we present a computational model for frequency stabilization of a laser source using ESC. The model is based on a saturated absorption spectroscopy experiment used to reference the frequency of the laser light to an atomic transition in Cesium atoms. By using this model, we were able to study the performance and adjust the parameters of the controlled system. This model was succesfully validated using an experimental open loop configuration. The model was then used to predict stable configurations of the controlled system, to be implemented in the experimental setup. As a result, we were able to get the laser frequency locked to a Cs atomic transition in the laboratory with a relative stability in frequency of 6x10-8.