The description below is from the book DOS the
Easy Way by Everett Murdock Ph.D.
for information about downloading the book.
Type: Internal (2.0 and later)
Purpose: Used in the CONFIG.SYS file to specify the maximum
files that can be open at the same time.
You should specify a FILES= value of at least 20 to satisfy most of
application programs. Some programs, such as Windows, may require as
many as 30
or 40 files. If you have not allocated enough files for an application,
error message may be displayed. If this happens, increase the number of
available and restart your computer. You should be aware that some
change the FILES= value in your CONFIG.SYS file automatically. After
a new program, be sure to check your CONFIG.SYS file to make sure the
will work with your other applications.
For more information about the FILES command, see Chapter 6, Tips for Advanced Users, in the downloadable book DOS the Easy Way.
number - Specifies the maximum number (8 to 255) of open files that DOS
will allow. The default value is 8.
To set the maximum number of files that can be open at the same time to
40, enter the following in your CONFIG.SYS file: