It looks like Freemat 4.2 crashes in some cases of stack overflow. Here is an easy-to-reproduce example (observed with 4.2 on MacOSX 10.14.4), with a recursive implementation of the Fibonacci sequence.
function u = fibrec(n)
% computes the n-th term of the (0,1)-Fibonacci sequence; recursive version
a = 0;
b = 1;
if (n == 0)
u = a;
elseif (n == 1);
u = b;
else
u = fibrec(n - 2) + fibrec(n - 1);
end;
end
--> fibrec(5)
ans =
5
--> fibrec(100)
<crash></crash>