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From: greg@smash.CTS.COM (Greg Laskin)
Newsgroups: rec.games.hack,comp.sources.bugs
Subject: Re: Help w/ NETHACK & MSC v4.0
Message-ID: <104@smash.CTS.COM>
Date: Sun, 6-Sep-87 00:43:08 EDT
Article-I.D.: smash.104
Posted: Sun Sep  6 00:43:08 1987
Date-Received: Sun, 6-Sep-87 20:59:08 EDT
References: <616@hadron.UUCP< <3470@zen.berkeley.edu< <1079@bsu-cs.UUCP<
Reply-To: greg@smash.CTS.COM (Greg Laskin)
Organization: Trailing Edge Technology, Redondo Beach, CA
Lines: 46
Xref: mnetor rec.games.hack:1368 comp.sources.bugs:272


In article <1079@bsu-cs.UUCP< dhesi@bsu-cs.UUCP (Rahul Dhesi) writes:
<In article <3470@zen.berkeley.edu< iverson@cory.Berkeley.EDU.UUCP (Tim 
<Iverson) writes (about setting a stack for hack.exe under MSDOS):
<
<<I tried stacks up to 64k, but I always
<<got the same lack of stack space.  Then I tried smaller stacks - and guess
<<what?  It worked!  The limit is somewhere between 0a00 and 0b00 (a00 works
<<fine, but b00 doesn't).  If someone out there understands exactly why it
<<works with a small stack but not a large one, I'd really like to know.
<
<A lot of things under MS-DOS are measured in units of 16-byte clicks.
<Thus, when you specify a stack of 0xa00 bytes, you may be really
<specifying 0xa00 clicks, which is 0xa000 bytes or 40 kilobytes.  Since
<the stack segment can't exceed 64 kilobytes, specifying too large a
<stack will cause overflow.  Unfortunately, the Microsoft linker doesn't
<seem to give a warning when this happens, and just seems to use some
<unknown value instead.
<
This is incorrect.  The -F switch specification gives stack size in BYTES
not PARAGRAPHS.  -F 0A00 gives a stack of 2.5K.  The default is 2K.

<Also note that, depending upon the memory model and the options you
<specify to the compiler, the stack may share a segment with static
<(non-stack) data, limiting the stack itself to less than a full
<segment.

There is an upper bound to the size of the stack.  That is the space left
in the _DATA segment after everything else gets stuffed in it.  The _DATA
segment gets all the static initialized variable including "string"
constants.  If you look at a map (link with -m hack.map) you'll see
that there's very little space left for the stack in _DATA.  _DATA
is limited to 64K total.

You can use -Gt# to place initialized variables ># in size in a separate
module, thus removing them from _DATA and leaving more room for the 
stack.  




-- 
Greg Laskin           
"When everybody's talking and nobody's listening, how can we decide?"
INTERNET:     laskin@gryphon.CTS.COM
UUCP:         {hplabs!hp-sdd, sdcsvax, ihnp4, nosc}!crash!gryphon!laskin