I ran your code with the loop iterator set 1e6, and see no memory growth under either 5.8.6 or 5.8.8.

I seem to recall that 5.8.2 (the version shown in your OP), was a particularly buggy, short-lived release. I strongly suggest you try upgrading to something newer. My memory tells me that 5.8.3 was a pretty good build as is 5.8.6 which I still use as my default install. I encountered a few problems with 5.8.8 but I think they may have been limited to the AS-Win distribution I use.