  We study dilaton stabilization in heterotic string models. By utilizing the
asymmetric orbifold construction, we construct an explicit three-generation
model whose matter content in the visible sector is the supersymmetric standard
model with additional vectorlike matter. This model does not contain any
geometric moduli fields except the dilaton field. Model building at a symmetry
enhancement point in moduli space enlarges the rank of the hidden gauge group.
By analyzing multiple hidden gauge sectors, the dilaton field is stabilized by
the racetrack mechanism. We also discuss a supersymmetry breaking scenario and
F-term uplifting.
