[Closed] is there some ways to cache shadow maps?

please help
i need cached shadow maps. i.e. i render shadow maps оnce and save them to disk and then can use it without recalculating. this can greatly speed-up animation renderings.
similar feature can be found in mental ray or final render renderers (FR shadow maps are very cool indeed). but i cannot use neither of them.
does anyone knows the solution for this problem?