DOS Fn 67H: Set File Handle Count

                                                         Compatibility: 3.3+ 
 Expects: AH    67H
          BX    desired maximum number of file handles
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 Returns: AX    error code if CF is set to CY
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    Info: This function sets the maximum number of file handles that can be
          open concurrently by the calling program.

          BX can range from 20 to 65535.  If less than 20, 20 is used.

          If BX is less than the current maximum (that is, if you want to
          shrink the number of handles) and more than BX files are
          currently open, then the change will be delayed until there are
          no more than the desired number of handles open.

          If BX is greater than the current maximum (you want to increase
          the number of handles), then DOS must have memory available to
          allocate space for the new handles.  Use DOS Fn 4aH (SetBlock) to
          shrink the current memory usage.  See Accessing Upper Memory for
          a way to put handles in UMB▲ space.

   Notes: ■ By default, the file handle table is contained in a reserved
            portion of each program's PSP.  This call tells DOS to allocate
            some memory for an enlarged table.

          ■ This affects only the current application.  The number of
            handles available to the system itself is set by the FILES=
            command in CONFIG.SYS.  It does not affect child processes.

          ■ Remember that by default, 5 handles are used for standard I/O
            devices.

See Also: Handle-Oriented File I/O
          CONFIG.SYS
          DOS Functions
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