This should save a lot of memory on many method calls.

The stack will have a guaranteed zone which is always available. The size of the guard area will be target specific. It will include enough stack space to actually allocate more stack space. Each function will have to verify that
it has enough space in the current stack to execute.

An implicitly typed local variable is strongly typed just as if it had been declared the type, but the compiler determines the type. The following two declarations of $i are functionally equivalent:
int $i = 10; // Explicitly typed.
auto $i = 10; // Implicitly typed.