VMS Help Sys Parameters, PAGEDYN  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    PAGEDYN sets the size of the paged dynamic pool in bytes. The
    specified value is rounded down to an integral number of pages.
    Each page of paged dynamic pool adds 8 bytes of permanently
    resident memory to the system page table; the paged dynamic pool
    has no other direct memory requirements.

    The paged dynamic pool is used to allocate storage for shared
    logical names, resident image headers, known file list entries,
    and RMS file-sharing structures. Substantial amounts of space
    for the pool can be overallocated with little effect on system
    performance.

    The size of the paged pool can grow dynamically up to the maximum
    size that this parameter specifies.

    PAGEDYN has AUTOGEN, FEEDBACK, GEN, and MAJOR attributes.