Page allocation map describes the current DSA usage. Each PAM subpool entry is 16 bytes long describing each subpool. It records the subpool ID and the number of pages assigned in the subpool. It also contain the FAQE pointers which chain up the free area ms within the pages which can be used for future requests. Program subpool does jot uses FAQE because the basic allocation for program is on page. Task storage also does not use FAQE. He pointers are kept in TCA instead.
PAM also contains other fields like page size of DSA, the cushion size, the address of the first DSA page etc.
the address shifting factor field contain a value depending on the page size (2K or 4K) and is used with the starting virtual address of DSA to conveniently deride the DsA page number for an arbitrary address or to locate the starting address of an arbitrary DSA page
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