用户提出申请存储器空间时，存储管理必须根据申请者的要求，按一定的策略分析主存空间的使用情况，找出足够的空闲区域分配给申请者。-User application memory space, storage management must be based on the applicant' s request, according to a certain strategy of the use of main memory space, to find enough free area a