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 Some older application programs use file control blocks

(FCBs) instead of the newer file handles to create, open, and

delete files as well as to read from and write to files. When

using these programs on a network with file sharing in use, you

may have to increase the number of files that can be opened by

FCBs. The default value used by DOS is 4 files.

To specify a new number of files that can be concurrently

open by DOS, you use the FCBS command in the CONFIG.SYS file:

FCBS = x,y

where

x Specifies the total number of files that can

be opened by FCBs.

y Specifies the number of files protected from

automatic closure by DOS (the default is 0).

When file sharing is in use and an application program tries

to open more than the total number of files, DOS closes the

least-recently used file and opens the new file (excluding the

files protected from automatic closure). If the program tries to

read from or write to a file that has been closed by DOS, you

will receive the following error message:

FCB unavailable

Abort, Fail?

To avoid such an error, you would add a FCBS command to your

CONFIG.SYS file. For example, entering

FCBS = 10,5

would allow 10 FCB files to be open concurrently and would

protect 5 of these from automatic closure.

When specifying the first parameter (the total number of FCB

files), you can enter a value between 1 and 255. When specifying

the second parameter (the number of files protected from

automatic closure), you can enter a value between 0 and 255.