Virtual regions begin at the top of the system region (see Figure 1) and are allocated upward through the user region to the bottom of the area containing the LSQA, SWA, and the user key area (subpools 229, 230, and 249). Virtual regions are allocated above 16 megabytes also, beginning at the top of the extended CSA, and upward to the bottom of the extended LSQA, SWA, and the user key area (subpools 229, 230, and 249).

As a portion of any V=V job is paged in, 4K multiples (each 4K multiple being one page) of central storage are allocated from the available central storage. Central storage is dynamically assigned and freed on a demand basis as the job executes. V=V region requests that specify a specific region start address, are supported only for restart requests, and must specify an explicit size through JCL (see Specifying region size).