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Format of data at start of STACKS code segment (if present)

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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.

See Also:

#01636,INT B4"STACKMAN"