In the notes later in this section, "subtaskn" refers to subtask1 for the F1 file or subtask2 for the F2 file.

• Since a JOINKEYS application uses three tasks, it can require more storage than a regular DFSORT application. You may need to use REGION=0M for some JOINKEYS applications.
• DFSORT's normal syntax and continuation rules are used for the JOINKEYS, JOIN and REFORMAT statements. See Using DFSORT program control statements for details.
• Control statements from DFSPARM, SYSIN (direct invocation) or SORTCNTL (program invocation) will be used for the main task, but not for the subtasks. Control statements from JNF1CNTL will be used for subtask1. Control statements from JNF2CNTL will be used for subtask2.
• For the main task, the normal options in effect for a DFSORT run will be used. The run-time options will be those from DFSPARM, SYSIN, SORTCNTL, EXEC PARM or the caller's parameter list, as appropriate. The installation options will be those for direct invocation or program invocation of DFSORT, as appropriate.
• For subtaskn, the options in effect for the subtask will be used with the exceptions noted later in this section. The run-time options will be those from JNFnCNTL. The installation options will be those for a calling program (INV, TSOINV, TD1-TD4).
• TYPE=F processing is used for a VSAM F1 or F2 file by default. TYPE=V can be specified in JNFnCNTL, or on the JOINKEYS statement for Fn, to override the default of TYPE=F.
• For subtaskn, if an INCLUDE or OMIT statement or a STOPAFT or TYPE option is specified in JNFnCNTL, it will override the corresponding option in a JOINKEYS statement for Fn. For ease of use, it is recommended that you use an INCLUDE or OMIT statement, and a STOPAFT or TYPE option, in JNFnCNTL rather than an INCLUDE, OMIT, STOPAFT or TYPE operand in a JOINKEYS statement.
• For the main task, override of statements and options is done in the normal way, that is, DFSPARM overrides SYSIN for direct invocation of DFSORT, and DFSPARM overrides SORTCNTL overrides the caller's parameter list for program invocation of DFSORT. See Using DFSORT program control statements for details.
• The following options will be used for subtaskn and cannot be overridden: LIST, MSGPRT=ALL, NOABEND, ESTAE, NOCHECK, EQUALS and RESINV=0. DYNALLOC will be used automatically for subtaskn, but can be overridden by a DYNALLOC option in JNFnCNTL.
• If an INCLUDE or OMIT statement is specified in JNFnCNTL, DFSORT will use the following options in effect for subtaskn processing: ALTSEQ, CHALT or NOCHALT, SZERO or NOSZERO and VLSCMP or NOVLSCMP. These options can be specified in JNFnCNTL. The subtaskn LOCALE installation option in effect will also be used if appropriate.
• If an INCLUDE or OMIT operand is specified on the JOINKEYS statement for Fn, DFSORT will use these main task options in effect for subtaskn processing: ALTSEQ, CHALT or NOCHALT, SZERO or NOSZERO and VLSCMP or NOVLSCMP. If these options are specified in JNFnCNTL, they will be ignored for subtaskn processing. LOCALE will not be used.
• For subtaskn, the following statements are not allowed in JNFnCNTL: JOINKEYS, JOIN, MERGE, OUTFIL, OUTREC, REFORMAT and SORT.
• For the main task, a MERGE statement other than MERGE FIELDS=COPY is not allowed in any source.
• If appropriate, options such as FILSZ, DYNALLOC, AVGRLEN, and so on can be specified in JNFnCNTL for subtaskn, or in DFSPARM for the main task.
• If tape data sets are used for the F1 and F2 files, they must be on different drives so DFSORT can read them in parallel.