Place variables frequently used by the same function on the heap?

Say that I have the following situation:

void myFunc()
{
    int x;
    //Do something with x
}

"x" is placed on the stack which is no doubt fast.

Now, "myFunc" is called very frequently, lets say 10 times per second. Is it plausible to do something like this:

int x;
void myFunc()
{
    //Do something with x
}

so that x gets allocated in the applications data segment. but it is allocated only once. Since "myFunc" is called so frequently, does the second approach deliver any performance benefits?