Most jobs are not allowed to use all of their address space, or allowed to store on disk in the swap area a page for each byte of their virtual address space. For a 32-bit machine, this would require about 4 billion bytes per job. (This is 4 gigabytes.) The more typical situation is to assign a small amount of memory to each job, such as 8 megabytes, and if it grows into unused regions of its stack or heap, additional pages are allocated, up to a limit determined by the system administrator.