start_va_64

    OpenVMS usage:address
    type:         quadword address
    access:       read only
    mechanism:    by value
    The starting virtual address of the pages to be locked in the
    working set. The specified virtual address will be rounded down
    to a CPU-specific page boundary.

 length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       read only
    mechanism:    by value
    Length of the virtual address space to be locked in the working
    set. The specified length will be rounded up to a CPU-specific
    page boundary so that it includes all CPU-specific pages in the
    requested range.

 acmode

    OpenVMS usage:access_mode
    type:         longword (unsigned)
    access:       read only
    mechanism:    by value
    Access mode associated with the pages to be locked. The acmode
    argument is a longword containing the access mode.

    The $PSLDEF macro in STARLET.MLB and the file PSLDEF.H in
    SYS$STARLET_C.TLB define the following symbols and their values
    for the four access modes:

    Value      Symbolic Name      Access Mode

    0          PSL$C_KERNEL       Kernel
    1          PSL$C_EXEC         Executive
    2          PSL$C_SUPER        Supervisor
    3          PSL$C_USER         User

    The most privileged access mode used is the access mode of the
    caller. For the $LKWSET_64 service to complete successfully, the
    resultant access mode must be equal to or more privileged than
    the access mode already associated with the pages to be locked.

 return_va_64

    OpenVMS usage:address
    type:         quadword address
    access:       write only
    mechanism:    by 32- or 64-bit reference
    The lowest process virtual address of the pages locked in the
    working set. The return_va_64 argument is the 32- or 64-bit
    virtual address of a naturally aligned quadword into which the
    service returns the virtual address.

 return_length_64

    OpenVMS usage:byte count
    type:         quadword (unsigned)
    access:       write only
    mechanism:    by 32- or 64-bit reference
    The length of the virtual address range locked in the working
    set. The return_length_64 argument is the 32- or 64-bit virtual
    address of a naturally aligned quadword into which the service
    returns the length of the virtual address range in bytes.