Defined in alloca.h, this function allocates
local storage in a function. It returns a pointer to size bytes
of memory. The default implementation returns an eight-byte aligned
block of memory on the stack.
Memory returned from alloca() must never
be passed to free(). Instead, the memory is de-allocated
automatically when the function that called alloca() returns.
Note
alloca() must not be called through a
function pointer. You must take care when using alloca() and setjmp() in
the same function, because memory allocated by alloca() between
calling setjmp() and longjmp() is
de-allocated by the call to longjmp().
This function is a common nonstandard extension to many C libraries.
Syntax- Reference
Using ARM® C and C++ Libraries and Floating-Point Support:
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