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musicale • last Sunday at 8:34 PM • 2 replies • view on HN

The PL/I stack growing up rather than down reduced potential impact of stack overflows in Multics (and PL/I already had better memory safety, with bounded strings, etc.) TFA's author would probably have appreciated the segmented memory architecture as well.

There is no reason why the C/C++ stack can't grow up rather than down. On paged hardware, both the stack and heap could (and probably should) grow up. "C's stack should grow up", one might say.

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Joker_vD • last Sunday at 8:51 PM

> There is no reason why the C/C++ stack can't grow up rather than down.

Historical accident. Imagine if PDP-7/PDP-11 easily allowed for the following memory layout:

    FFFF +---------------+
         |     text      |  X
         +---------------+
         |    rodata     |  R
         +---------------+
         |  data + bss   |  RW
         +---------------+
         |     heap      |
         |      ||       |  RW
         |      \/       |
         +---------------+
         |  empty space  |  unmapped
         +---------------+
         |      /\       |
         |      ||       |  RW
         |     stack     |
    0000 +---------------+
Things could have turned out very differently than they have. Oh well.
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josephg • last Sunday at 10:04 PM

Is there anything stopping us from doing this today on modern hardware? Why do we grow the stack down?

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