INT 67 - LIM EMSsee Expanded Memory Specification 4.0 - ALTER PAGE MAP AND CALL
	AH = 56h
	AL = subfunction
	    00h physical page numbers provided by caller
		DX = handle
		DS:SI -> structure containing page map and call address
	    01h segment addresses provided by caller
		DX = handle
		DS:SI -> structure containing page map and call address
	    02h get page map stack space required
		Return: BX = stack space required
Return: (if successful, the target address is called.  Use a RETF to return
	 and restore mapping context)
	AH = status (00h,80h,81h,83h,84h,8Ah,8Bh,8Fh) (see #03648)
SeeAlso: AH=55h