INT 31 P - CauseWay v1.3 - "GetMCBSize" - GET CURRENT MCBsee Memory Control Block ALLOCATION BLOCK SIZE
	AX = FF27h
Return: ECX = current threshold
Desc:	determine the memory allocation size below which CauseWay will use
	  internal MCBsee Memory Control Block chains rather than allocating full 4K pages via DPMIsee DOS Protected-Mode Interface
SeeAlso: AX=FF00h,AX=FF28h