MFX can process multiple VSAM and non-VSAM data sets for input through the MULTIIN facility. This facility enhances the standard SORTIN specification which supports only a single VSAM data set for input without any concatenation of VSAM or non-VSAM data sets. The MULTIIN facility can be used for a SORT or COPY application.
MULTIIN may also be used in any multiple input file application where there is a need to identify the data set from which a record was read. The &MULTIINDD subparameter of the INCLUDE/OMIT control statements and the INREC control statement can be used for this purpose. See INCLUDE/OMIT Control Statement Format and INREC Control Statement Format for details.
If multiple files need to be processed as input, but there are no VSAM files and there is no need for the &MULTIINDD feature, conventional SORTIN concatenation should be used. This will improve the performance of the application.