Completing the data control block

The system obtains data control block information from the following sources, in override order:
  • The processing program, that is, the DCB macro instruction in assembler language programs or file definition statements or language-defined defaults in programs in other languages.
  • The DCB subparameter of the DD statement.
  • The data set label.

Therefore, if you supply information for the same DCB field in your processing program and on a DD statement, the system ignores the DD DCB subparameter. If a DD statement and the data set label supply information for the same DCB field, the system ignores the data set label information.

Note: When concatenated data sets are involved, the DCB is completed based on the type of data set and how the processing program uses the data set. See z/OS DFSMS Using Data Sets for more information.
Parent topic: DCB parameter