Format of data at start of STACKS code segment (if present):
Offset	Size	Description	)
 00h	WORD	???
 02h	WORD	number of stacks (the x in STACKS=x,y)
 04h	WORD	size of stack control block array (should be 8*x)
 06h	WORD	size of each stack (the y in STACKS=x,y)
 08h	DWORD	pointer to STACKS data segment
 0Ch	WORD	offset in STACKS data segment of stack control block array
 0Eh	WORD	offset in STACKS data segment of last element of that array
 10h	WORD	offset in STACKS data segment of the entry in that array for
		  the next stack to be allocated (initially same as value in
		  0Eh and works its way down in steps of 8 to the value in
		  0Ch as hardware interrupts pre-empt each other)
Note:	the STACKS code segment data may, if present, be located as follows:
    DOS 3.2:	The code segment data is at a paragraph boundary fairly early
		  in the IBMBIO segment (seen at 0070:0190h)
    DOS 3.3:	The code segment is at a paragraph boundary in the DOS data
		  segment, which may be determined by inspecting the segment
		  pointers of the vectors for those of interrupts 02h, 08h-0Eh,
		  70h, 72-77h which have not been redirected by device drivers
		  or TSRs.
    DOS 4.0+	Identified by sub-segment control block type "S" within the DOS
		  data segment.
SeeAlso: #01636,INT B4"STACKMAN"