Another rule of thumb. If recovering from a stall at (say) 37,000 ft, lower the nose to just below the horizon and keep it there until reaching Vref 40 plus 100 knots (737) or approx. 230-240 IAS then gently level out. Count on losing at least 3000 feet. This figure from the 737 FCTM for best holding speed above 25,000 ft if FMC not available. If stall was due to mishandling in severe turbulence, then increase to severe turbulence speed before attempting to level out.