The Free On-line Dictionary of Computing (30 December 2018):

CONFIG.SYS

    A text file containing special system
   configuration commands, found in the root directory on an
   MS-DOS computer, typically on drive C (the hard disk).  It
   is read by MS-DOS at boot time, after the setup has been read
   from CMOS RAM and before running AUTOEXEC.BAT.  It can be
   modified by the user.

   Some example commands which CONFIG.SYS might contain are:

   	DEVICE=C:\DOS\HIMEM.SYS /testmem:off

   Load the extended memory manager.

   	DEVICE=C:\DOS\EMM386.EXE RAM

   Load the expanded memory manager.

   	BUFFERS=10,0

   Specify memory for disk buffers.

   	FILES=70

   Set the number of files that can be open at once.

   	DOS=UMB

   DOS is located in UppeMemoryBlock.

   	LASTDRIVE=Z

   Disk drives are A: to Z:.

   	FCBS=16,0

   Set the number of file control blocks.

   	DEVICEHIGH /L:1,12048 =C:\DOS\SETVER.EXE

   Report the DOS version to older programs.

   	DOS=HIGH

   DOS should maintain a link to UMB.

   	COUNTRY=358,437 C:\DOS\COUNTRY.SYS

   Set the country code for some programs.

   	STACKS=9,256

   Set dynamic stacks for hardware control.

   	SHELL=C:\DOS\COMMAND.COM C:\DOS\ /E:1024 /p

   Set the location of the command interpreter.

   (1995-03-16)