System Area occupies the low address range. System Area contains the nucleus load modules and nucleus extension. Nucleus load modules contains the dispatcher, interrupt handler and recovery support code. Nucleus also contains the CVT and page frame table. Nucleus extension contains fixed BLDL tables (device address of the program entries), fixed link pack area and other system-wise information. Nucleus starts at address 0 and the virtual addresses of System Area is same as real addresses.
Private Area is above the System Area. Private Area contains the user program in a region specified in the JOB card. To keep track of works and stroage in region, the Private Area also contains the LSQA and SWA. LSQA contains CB and tables related to the address space such as the segment table and page table. Subpool 253, 254 and 255 are in LSQA.
SWA is a work area of dispatcher. It contains subpool 236 and 237 which contains the job queue of the address space.
Private Area is pageable except the LSQA. When the address space is swapped in, LSQA will be fixed in real memory until the address space is swapped out.
Above Private Area is the Common Area. Common Area is common to all address spaces. Common Area contains the SQA, Pageable LPA and Common System Area. SQA contains tables and queues of the entire system and information related to all private address spaces. These information cannot be placed in LSQA which can be paged out with specific address space.
PLPA contains SVC routines, access method and other selected program. The routines are re-entrant. PLPA is pageable.
CSA is used for communication between address spaces.
System Area and Common Area are shared by and common to all address spaces. Their page tables are kept in SQA. Segment table and the private page tables are kept in LSQA
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