For the 737NG the following applies:
When cruising at or near 41,000 feet (Max.ALT according Limitations), the TCAS may issue a Climb RA. The flight crew should comply even if the maneuver causes a minor and brief climb above the maximum operational altitude as this allows TCAS to advise the best coordinated resolution maneuver. The airplane is still capable of maintaining a 2500 feet per minute climb rate at an altitude greater than the maximum operational altitude.
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