The SORTIN DD statement is required for a PARASORT application. It must define either a single multi-volume tape data set or several concatenated tape data sets, which can be single or multi-volume. If the SORTIN is concatenated, each data set must meet the normal SORTIN concatenation requirements and must be able to use the same device type so that UNIT=AFF=SORTIN can be specified for all data sets in the concatenation. For a discussion of normal SORTIN JCL, see JCL and Sample JCL/Control Statement Streams.
For optimal performance, data sets that reside on tapes, such as 3480s, that can be read only in a single direction should have two units allocated. If the data set is on a tape that supports bidirectional processing, a single unit is sufficient. In all cases DEFER mounting must be specified.
SORTIN data sets may not be passed data sets or have PASS specified on their DD statement.
Either the catalog or specific list of volume serial numbers must be specified. The volume serial list must accurately reflect the volumes in the data set. If extra volumes are specified (as may happen if an old data set is rewritten with less data) an error message will be generated. A volume sequence number may not be specified.
The following example SORTIN DD statements for PARASORT illustrate three different SORTIN cases:
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A multi-volume cataloged data set
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A multi-volume uncataloged data set
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Concatenated single and multi-volume uncataloged data sets
Note that each example includes a y on the UNIT specification (for example, UNIT=(3480,y,DEFER)). The y is either 1 or 2 and indicates the number of units to be allocated for these devices. For optimal performance, data sets that reside on tapes that can be read only in a single direction, such as 3480s, should have two units allocated. If the data set is on a tape that supports bidirectional processing, a single unit is sufficient. In all cases DEFER mounting must be specified.
Note also that each example includes an alternative UNIT specification: UNIT=(xxxxx1,y,DEFER). This specification applies if special esoteric names are available. The xxxxx1 is a special esoteric unit name established especially for PARASORT. These esoteric names may have been created at your site for use with PARASORT. Contact the systems programmer responsible for MFX installation to determine if they are available. For information on how to select a special esoteric name, see Special Channel Separated Esoteric Names.
Example 1
Example 2
This example presumes the file is standard label and the first file is on VOL001.
For uncataloged data sets, the unit and volser list must be specified.
Example 3
It is also possible to include a DD DUMMY allocation in the SORTIN concatenation. This is necessary when modifying production JCL that is a prototype for the maximum number of possible concatenated input files. If a particular execution uses less than the maximum number, place the DD DUMMY specification at the appropriate point. This specification should contain a DCB specification that matches that of the first SORTIN data set.