This paper advocates the use of 3D integration technology to stack a DRAM on top of an FPGA. The DRAM will store future FPGA contexts. A configuration is read from the DRAM into a latch array on the DRAM layer while the FPGA executes; the new configuration is loaded from the latch array into the FPGA in 60ns (5 cycles). The latency between reconfigurations, 8.42 mu s, is dominated by the time to read data from the DRAM into the latch array. We estimate that the DRAM can cache 289 FPGA contexts.