One embodiment of the present invention provides a system for allocating storage space for objects within a persistent object system. The persistent object system includes an object heap that is organized into a young generation region and an old generation region. The system uses the young generation region for newly created objects and uses the old generation region for objects that have not been removed by several garbage collection cycles. The system allocates storage space for new (transient) objects in the young generation region of the object heap. Periodically, the system copies the transient objects from the object heap to a stable store to form a checkpoint of the system state. Transient objects become persistent objects when they are copied to the stable store. Persistent objects are removed from the object heap when the system is stopped and when room is needed in the object heap for additional objects. When a persistent object that has been removed is referenced during execution of a computer program, the system faults the persistent object directly into the old generation region of the object heap from the stable store.