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

    (VAX only) INTSTKPAGES sets the size of the interrupt stack
    in pages. Each page on the interrupt stack requires a page of
    permanently resident memory.

    Use the default value of 6 unless interrupt-stack-not-valid
    exceptions occur. These may be caused by either an unusually
    large number of devices or a driver that requires a large amount
    of stack space.

    INTSTKPAGES has AUTOGEN, DYNAMIC, GEN, and MAJOR attributes.