On Alpha and Integrity server systems, locks a range of pages in
    memory. The specified virtual pages are forced into the working
    set and then locked in memory. A locked page is not swapped out
    of memory if the working set of the process is swapped out. These
    pages are not candidates for page replacement and, in this sense,
    are locked in the working set as well.

    This service accepts 64-bit addresses.

    Format

      SYS$LCKPAG_64  start_va_64 ,length_64 ,acmode ,return_va_64

                     ,return_length_64

    C Prototype

      int sys$lckpag_64  (void *start_va_64, unsigned __int64

                         length_64, unsigned int acmode, void

                         *(*(return_va_64)), unsigned __int64

                         *return_length_64);

1  –  Arguments

 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. 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. 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 $LCKPAG_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 memory.
    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 32- or 64-bit virtual address of a naturally aligned quadword
    into which the service returns the length of the virtual address
    range locked in bytes.