MS-DOS 6.22 COMMAND.COM Environment Size

This article explains how to configure the primary environment size in MS-DOS 6.22 using the COMMAND.COM interpreter. You will learn the exact command-line parameter required to expand environment space, the allowed values, and how to apply this setting permanently using the CONFIG.SYS file to resolve "Out of environment space" errors.

In MS-DOS 6.22, the parameter used to specify the environment size in COMMAND.COM is the /E: switch.

Syntax and Parameters

The syntax for setting the environment size is:

COMMAND.COM /E:size

/E:size specifies the environment size in bytes.
size must be an integer ranging from 160 to 32,768.
If you specify a value smaller than 160, MS-DOS defaults to 160 bytes.
If you specify a value larger than 32,768, MS-DOS defaults to 32,768 bytes.
The default environment size in MS-DOS 6.22 without this parameter is 256 bytes.

How to Configure the Primary Environment Size

To permanently set the primary environment size for your MS-DOS system, you must define it in the CONFIG.SYS file using the SHELL command.

Open C:\CONFIG.SYS in a text editor like MS-DOS Editor:
```
EDIT C:\CONFIG.SYS
```
Locate or add the SHELL directive. Include the /E: switch along with the /P (permanent) switch:
```
SHELL=C:\DOS\COMMAND.COM C:\DOS\ /P /E:1024
```
- C:\DOS\COMMAND.COM specifies the path to the command interpreter.
- C:\DOS\ specifies the directory where COMMAND.COM looks for itself when reloading.
- /P instructs DOS to make this instance of COMMAND.COM permanent and to automatically execute AUTOEXEC.BAT upon boot.
- /E:1024 sets the primary environment size to 1,024 bytes.
Save the file and reboot the computer for the changes to take effect.

Secondary Shell Usage

The /E: parameter can also be used when spawning a secondary shell from the command line. For example:

COMMAND /E:2048

This opens a new command processor session with 2,048 bytes of environment space, which remains active until you type EXIT to return to the parent shell.