SORTINnn and SORTINn DD statements are used to define the input to a merge application. (Use the SORTIN DD statement to define the data set to be sorted or copied.) SORTINnn or SORTINn DD statements are required for all merge applications unless an E32 exit supplies the input data. SORTINnn and SORTINn data sets may be BatchPipes or z/OS pipes or they may be HFS data sets. Since all input data sets are open at the same time during a merge, UNIT=AFF cannot be coded on any of the input DD statements.
It is possible to merge up to 100 data sets. Each input data set is specified on a SORTINnn or SORTINn DD statement. The valid range for n is 0 through 9; for nn, 00 through 99. If both SORTINx and a SORTIN0x are specified, they are treated as duplicates and only the first definition is processed. Each file must receive a different number. Numbers may be skipped or used out of order. There are no restrictions as to which input files are to receive which numbers.
All input data sets must have the same record format (fixed or variable), and the records in each input file must already be in the desired sequence.
By default, MFX does not accept an uninitialized SORTINnn or SORTINn data set and will terminate processing with a WER400A message. An uninitialized data set is one that has been newly created, but never successfully closed. The UNINTDS PARM or installation option can be used to change MFX’s default mode of processing to accept an uninitialized input data set and process it as an empty file. (See UNINTDS.)
In this example, the DCB information for the first two of the three files to be merged is supplied by the file labels. In order for the merge to execute, these files must have a RECFM of F or FB, as indicated by the third file’s RECFM value.