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check_stack
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─────C/C++ Language─────────────────────────────────────────────────────────
Pragma: check_stack
Syntax: #pragma check_stack ([{ on | off }])
Summary: Instructs the compiler to turn off stack probes if "off" is
specified, or to turn on stack probes if "on" is specified.
If no argument is given, stack probes are treated
according to the default (on, unless /Gs was used).
See also: check_pointer
You can reduce the size of a program and speed up execution
slightly by removing stack probes. You can do this with either the
/Gs option or the check_stack pragma.
A "stack probe" is a short routine called on entry to a function
to verify that there is enough room in the program stack to
allocate local variables required by the function. The stack probe
routine is called at every function entry point. Ordinarily, the
stack probe routine generates a stack overflow message when it
determines that the required stack space is not available. When
stack checking is turned off, the stack probe routine is not
called, and stack overflow can occur without being diagnosed
(i.e., no error message is generated).
Use the /Gs option when you want to turn off stack checking for an
entire module (if you know that the program does not exceed the
available stack space). For example, stack probes may not be needed
for programs that make very few function calls, or that have only
modest local variable requirements. In the absence of the /Gs
option, stack checking is on.
Use the check_stack pragma when you want to turn stack checking on
or off for selected routines only, leaving the default (as
determined by the presence or absence of the /Gs option) for the
rest. When you want to turn off stack checking, put the following
line before the definition of the function that you do not want to
check:
#pragma check_stack( off )
Note that the preceding line disables stack checking for all
routines that follow it in the source file, not just the routines
on the same line. To reinstate stack checking, insert the
following line:
#pragma check_stack( on )
For earlier versions of Microsoft C, the check_stack pragma had a
different format: check_stack+ to enable stack checking and
check_stack- to disable stack checking. Although the Microsoft C
compiler still accepts this format, its use is discouraged, since
it may not be supported in future versions.
If no argument is given for the check_stack pragma, stack checking
reverts to the behavior specified on the command line: disabled if
the /Gs option is given, or enabled otherwise. The interaction
of the check_stack pragma with the /Gs option is explained in
greater detail below:
Compiled with
Syntax /Ox or /Ol? Action
#pragma check_stack() Yes Turns off stack
checking for routines
that follow
#pragma check_stack() No Turns on stack
checking for routines
that follow
#pragma check_stack( on ) Yes or no Turns on stack
checking for routines
that follow
#pragma check_stack( off ) Yes or no Turns off stack
checking for routines
that follow
The check_stack( off ) and /Gs options should be used with great
care. Although these options can make a program smaller and
faster, they may mean that the program will not be able to detect
certain execution errors.
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