The disturbance decoupling problem with stability (DDPS) and simultaneous infinite-time horizon optimal L-Q regulation, for continuous time-invariant linear systems, is formulated as a parameter optimization problem in L-Q regulators subject to control constraints imposed by the solution of DDPS. For computational solution of DDPS an efficient numerical procedure is proposed which gives the solution directly in the form of constraints on some parameters of the state-feedback matrix. For computational solution of the optimization problem a specialized hybrid descent method is proposed composed by a sequence of steps of modified Newton, Newton’s and Quasi-Newton methods, suitable for problems with severe control structural constraints.