Data Control Block
In IBM mainframe operating systems, such as OS/360, MVS, z/OS, a Data Control Block (DCB) is a description of a dataset in a program. A DCB is coded in Assembler programs using the DCB macro instruction (which expands in a large number of "define constant" instructions). High level language programmers use library routines containing DCBs.
A DCB is one of the many control blocks used in these operating systems. A control block is basically a data area with a predefined structure, very similar to a C struct, but typically only related to system's functions. A DCB may be compared to a FILE structure in C, but it is much more complex, offering much more options for various access methods.
The control block acted as the interface between Logical IOCS and the application program.
The equivalent control block for IBM DOS/360,DOS/VSE and z/VSEoperating systems is a "DTF" (Define the file)
See also
- Data Set Control Block (DSCB), a part of VTOC
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