A method is provided for maintaining system state in semiconductor device having a first chip and a second chip, which are physically conjoined to form a stacked structure, wherein the first chip includes functional circuitry, and the second chip includes control circuitry for capturing and restoring a microarchitecture state of the functional circuitry of the first chip. The method includes initializing a system state of the semiconductor device and entering a wait state for a state capture triggering event. In response to an occurrence of a state capture triggering event, state data representing a current system state of the functional circuitry on the first chip is captured. The captured state data is transferred to the second chip through a system state I/O (input/output) interface of the second chip under control of the control circuitry on the second chip. A copy of the captured state data is then stored in a memory.