A design structure embodied in a machine readable medium used in a design process includes a cache structure having a cache tag array associated with a eDRAM data cache comprising a plurality of cache lines, the cache tag array having an address tag, a valid bit and an access bit corresponding to each of the plurality of cache lines; and each access bit configured to indicate whether the corresponding cache line has been accessed as a result of a read or a write operation during a defined assessment period, which is smaller than retention time of data in the DRAM data cache; wherein, for any of the cache lines not accessed as a result of a read or a write operation during the defined assessment period, the individual valid bit associated therewith is set to a logic state that indicates the data in the associated cache line is invalid.