XMS 0cH: Lock Extended Memory Block

                                                     Compatibility: XMS 2.0+ 
 Expects: AH    0cH
          DX    XMS handle (as obtained via XMS 09H)
 Returns: AX    status: 0000H = successful
                        0001H = error and BL=XMS error code (if BL >= 80H)
          DX:BX 32-bit linear address of base of block
    Info: This locks an extended memory block into place (XMM will not move
          its data around while locked) and returns a 32-bit linear address
          of the start of the block.

          The block should be unlocked as soon as possible (see XMS 0dH).

          The XMM maintains a "lock-count" and only allows the block to
          move when the lock count is decremented to 0.  XMS 0eH obtains
          the current lock count.

See Also: XMS Functions
          Extended Memory Specification (XMS)
          DOS Functions