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Utility Descriptions 5-59
STACKDEV.SYS
The STACKDEV.SYS command is used to increase the number of stacks
available for IRQ handlers and Int13h. The standard STACKS= command
for ROM-DOS increases stack space for the DOS stacks only.
Syntax
DEVICE=STACKDEV.SYS
Remarks
Under various conditions, a stack overflow error occurs while booting
ROM-DOS, usually during the CONFIG.SYS or AUTOEXEC.BAT file
processing. For example, some other program may service an interrupt
and not provide its own stack for that purpose. If, inside its interrupt
handler, the program consumes a lot of stack space by allocating many
automatic variables, calling other interrupt handlers, or by deeply nesting
sub-routines, then the interrupt handler may overflow the stack of the
program that it interrupted. This situation usually results in a system
crash. The STACKDEV.SYS device driver handles stack support similar
to MS-DOS’ internal Stacks support. STACKDEV increases the stack
space available for IRQ handlers and Int13h by switching to a local stack
each time an interrupt occurs. STACKDEV does not allocate the stacks
from a pool, instead, each interrupt on the list is given exactly one stack
with a fixed stack size of 128 bytes. STACKDEV differs from the internal
STACKS= support with ROM-DOS in that the STACKS= command is
used to allocate stack space for ROM-DOS’ own internal stacks and does
not add additional stack support for IRQs.
Examples
DEVICE = STACKDEV.SYS
Loads the STACKDEV.SYS device driver during CONFIG.SYS
processing. This driver should be loaded early in the file so that it can
handle the IRQ stack needs of other device drivers or programs.