Library /sys$common/syshlp/sysmanhelp.hlb RESERVED_MEMORY, ADD, Qualifiers, /ZERO  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /ZERO
       /NOZERO (default)

    /ZERO implies /ALLOCATE. If you specify /ZERO, pre-allocated
    pages are zeroed during system initialization. Zeroed pages are
    required for memory-resident global sections; however, the pages
    do not need to be zeroed during system initialization.

    /NOALLOCATE implies /NOZERO because /ZERO is incompatible with
    /NOALLOCATE. If you do not specify /ZERO, or if you specify
    /NOZERO, pre-allocated pages are not zeroed during system
    initialization. Instead, these pages are zeroed when the global
    section is created.