producing die region wear-out data for a die region in each die of a plurality of stacked dies, the die region wear-out data representing a cumulative amount of time each of the plurality of die regions has spent at an operating condition based on operating condition data from each of the plurality of die regions, wherein the operating condition data is based on at least one of the following operating characteristics: frequency of operation of the plurality of die regions, an operating voltage of the plurality of die regions and an activity level of the plurality of die regions;

storing, in persistent memory, the die region wear-out data; and

spreading wear among the plurality of die regions using a spreading operation based on operating condition data that is not accumulated over a life of a respective die region, that overrides a thermal wear spreading operation that is based on the die region wear-out data from the persistent memory, that is accumulated over the life of the respective die region.