Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uwmcsd1!mrsvr!roth
From: roth@mrsvr.UUCP (The Unknown Programmer)
Newsgroups: comp.sys.ibm.pc
Subject: Increasing environment space
Summary: Depends on which DOS version!
Message-ID: <354@mrsvr.UUCP>
Date: 26 Aug 88 14:01:38 GMT
References: <1320@number1.step.UUCP> <8324@conexch.UUCP>
Organization: GE Medical, MR Center, Milwaukee
Lines: 59

> In article <1320@number1.step.UUCP> perl@step.UUCP (Robert Perlberg) writes:
> -I just tried adding another directory to my PATH in the autoexec.bat
> -file, and when I boot, I get "out of environment space".  How can I
> -increase the initial allocation of environment space so that the set's
> -in my autoexec.bat will succeed?


Once again.  The method used to increase the environment size
depends on the DOS version *AND* the OEM that mucked up the
MS-DOS version it used.

DOS versions 3.2+ can use the COMMAND.COM argument /E:xxxx to
change the environment size.  (See other messages for details,
or some DOS book or official DOS manual.)


*SOME* DOS version 3.1 can also change the environment size,
though the size to be sepcified is in different units than
for post 3.1.  Not all 3.1 versions can change the environment size
via "/E:"!  The OEM version 3.1 version that came with my system
cannot.

The environment size for DOS versions that do not accept the /E:
argument to COMMAND.COM can still be changed by modifying a couple
of bytes in COMMAND.COM that set the environment size.  I do not
have that information, but it should be noted that some DOS computers
are stuck at pre 3.1 versions because the manufacturer created 
a less-than 100% compatible system.


ALSO - not all DOS manuals for 3.1 document the /E: COMMAND.COM
argument. (And, as I've said, not all support it.  The version
of DOS that came with my clone does not support /E: and it is
supposed to be DOS 3.1.)


Note that creating a *large* environment (without saying what
"large" means) can create problems.  C programs typically
copy the environment onto its stack, and do so for each child
task.  A "large" environment can blow the stack.

Some problems have also been reported when using a
second copy of COMMAND.COM
on top of a copy that has a "larger" environment - the second
copy may not recognize the first copy has a "larger" environment.
(For example, escaping to the shell from a communications program.)



Dean A. Roth

roth@mrsvr.UUCP
{rutgers, uwvax} uwmcsd1!mrsvr!roth

deanr@lakesys.UUCP
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P.O. Box 11095
Milwaukee, WI 53211