Path: utzoo!attcan!uunet!husc6!cmcl2!phri!dasys1!tneff
From: tneff@dasys1.UUCP (Tom Neff)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Another twist on DOS environment sizes.
Summary: allocate dummy env variable before shelling
Message-ID: <4598@dasys1.UUCP>
Date: 24 May 88 15:54:43 GMT
References: <629@fxgrp.UUCP>
Reply-To: tneff@dasys1.UUCP (Tom Neff)
Organization: Independent Users Guild
Lines: 27

In article <629@fxgrp.UUCP> ljz%fx.com@ames.arc.nasa.gov (Lloyd Zusman) 
points out that most programs don't allocate any extra environment
space when shelling down to COMMAND.COM, regardless of whether you have
done so yourself at the top level with a /E:XXXX switch in CONFIG.SYS.
Instead, the shelled process gets an environment segment just large
enough to contain the SETs used by the parent process, leaving little
or no room for expansion at the child level.

He mentions two possible workarounds -- patching COMMAND.COM for a larger
default environment size, and including another /E:XXXX switch in each
COMMAND.COM line used for shelling.  Both have obvious limitations, and
he asks:
>Can any of you think of any other way around this problem?

Yes.  Before you shell, issue a dummy SET XX=XXXXXXX.... of sufficient
length to (a) cover your child process's anticipated needs, or (b) fill
the environment segment, whichever.  Then when your child process receives
control from the shell operation, the first thing it does is clear the
dummy SET leaving lots of free space to work with.

This is guaranteed to work with all flavors of DOS and requires no special
version specific knowledge, so I recommend it instead of patches etc.

-- 
Tom Neff			UUCP: ...!cmcl2!phri!dasys1!tneff
	"None of your toys	CIS: 76556,2536		MCI: TNEFF
	 will function..."	GEnie: TOMNEFF		BIX: are you kidding?