If anything didn&#x27;t happen in the past couple years, the article is correct. z&#x2F;Architecture doesn&#x27;t have non-executable memory nor ASLR. The reason I think is in part that they don&#x27;t have a free bit on each page descriptor to use.<p>Also, many mainframe programs are really old, and some may still rely on self-modification in unknown ways. And having ASLR would (IMHO) make debugging really painful, because they still rely on assembler programs a lot.<p>z&#x2F;OS (which drives development of z&#x2F;Architecture) is kind of Australia of operating systems. Early independent evolution -&gt; lot of weird and backward stuff there.