Open Merge for non-VSAM files is the process of consolidating the Data Control Block (DCB) attributes at file open, by filling in the blanks. If the process completes and DCB fields remain incomplete, a System 013 (OPEN) Abend occurs.
The columns below show the relationship of the various elements in the merge process. The primary source of DCB information is the Program. If all values are hard coded within the program, the values supplied in the Job Control and File Label will be ignored. The Job Control is the secondary source of DCB information and it will be scanned after the Program, but before the File Label. (To override File Label values, the values can be coded on the JCL provided they are not hard coded in the program.). The final source of DCB information is the File Label. (When reading files it is best to allow any residual values to be obtained from the File Label as these should be accurate.)
Clicking on the links in the table below will reveal a fuller description.
RECFM= |
RECFM= |
RECFM= |
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LRECL= |
LRECL= |
LRECL= |
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Not all DCB options are listed above, the aim was to illustrate the Open Merge Process using the commonest JCL parameters.
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