A method includes, if functional units assigned with multiple reserved areas is not driven, storing data with one of a data withdrawal condition set in the multiple reserved areas, and if the functional unit is driven, processing data stored in the one of the multiple reserved areas to restore the multiple reserved areas for driving the functional units based on the one of the data withdrawal condition set. An apparatus comprises a memory including multiple reserved areas and multiple non-reserved areas, wherein if a functional unit assigned with one of the multiple reserved areas is not driven, data is stored in the one of the multiple reserved areas with one of a data withdrawal condition set, and when the functional units is driven, data stored in the one of the multiple reserved areas is processed to restore the one of the multiple reserved areas.