ALLOCA(3) BSD Library Functions Manual ALLOCA(3)NAMEalloca — memory allocator
The alloca() macro allocates size bytes of space in the stack frame of
the caller. This temporary space is automatically freed on return.
RETURN VALUESalloca() returns a pointer to the beginning of the allocated space.
SEE ALSObrk(2), calloc(3), getpagesize(3), malloc(3), realloc(3)HISTORYalloca() appeared in Version 32V AT&T UNIX.
BUGSalloca() is machine and compiler dependent; its use is discouraged.
alloca() is slightly unsafe because it cannot ensure that the pointer
returned points to a valid and usable block of memory. The allocation
made may exceed the bounds of the stack, or even go further into other
objects in memory, and alloca() cannot determine such an error. Avoid
alloca() with large unbounded allocations.
The use of C99 variable-length arrays and alloca() in the same function
will cause the lifetime of alloca's storage to be limited to the block
containing the alloca()BSD September 5, 2006 BSD