How to Set Maximum Open Files in MS-DOS 6.22

In MS-DOS 6.22, the system configuration setting that controls the maximum number of files that can be open simultaneously is the FILES command. Configured inside the system's CONFIG.SYS startup file, this directive specifies how many file handles the operating system allocates in memory at one time, preventing software crashes and "Too many files open" errors.

The FILES Directive

The FILES command uses the following syntax:

FILES=n

The value n determines the maximum number of open files permitted system-wide.

  • Range: The value can range from 8 to 255.
  • Default: If the command is omitted entirely from CONFIG.SYS, MS-DOS 6.22 defaults to 8.
  • Recommended Value: Most MS-DOS 6.22 installations set this value between 30 and 50 to accommodate standard software, productivity suites, and database programs.

Memory Considerations

Each file handle allocated by the FILES directive consumes conventional memory. The base structure uses approximately 50 to 60 bytes of RAM per handle beyond the initial default. If your system loads DOS into the High Memory Area (using DOS=HIGH or DOS=HIGH,UMB along with HIMEM.SYS), MS-DOS automatically relocates the primary internal file tables to upper memory, preserving valuable lower conventional memory for applications.

How to Modify the Setting

To change the maximum number of open files in MS-DOS 6.22:

  1. Open the MS-DOS text editor by typing EDIT C:\CONFIG.SYS at the command prompt.
  2. Locate the existing FILES= line, or add it on a new line if it does not exist.
  3. Set the desired limit (for example, FILES=40).
  4. Save the file and exit the editor.
  5. Restart the computer for the changes to take effect.