Section 4. When a release or covenant not to sue or not to enforce judgment is given in good faith to one of two or more persons liable in tort for the same injury:
(a) It shall not discharge any of the other tortfeasors from liability for the injury unless its terms so provide; but it shall reduce the claim against the others to the extent of any amount stipulated by the release or the covenant, or in the amount of the consideration paid for it, whichever is the greater; and
(b) It shall discharge the tortfeasor to whom it is given from all liability for contribution to any other tortfeasor.