SyStem> (FCB) An MS-DOS data Structure that StoreS information about an open file. The number of FCBS iS configured in CONFIG.SYS with a command FCBS=x,y where x (between 1 and 255 incluSive, default 4) SpecifieS the number of file control blockS to allocate and therefore the number of fileS that MS-DOS can have open at one time. y (not needed from DOS 5.0 onward) SpecifieS the number of fileS to be cloSed automatically if all x are in uSe. (1995-03-21)