DFSORT Installation Basics (High Level)

Who Installs DFSORT?

System programmers (or installers) are responsible for installing and maintaining DFSORT (or the sort product your site uses). They use product-specific procedures (e.g. SMP/E for IBM products) to load the program libraries and to place the load modules (SORT, ICEMAN, ICETOOL, and related modules) in the appropriate load libraries. They also ensure that those libraries are in the link-list or otherwise available to batch and TSO users. As an application programmer, you do not usually perform the installation; you assume DFSORT is available and invoke it via JCL.

How the System Finds the Program

When your JCL says EXEC PGM=SORT, the system (MVS/job entry subsystem) must find a load module named SORT. It searches the load library concatenation: typically the link-list libraries first, then any JOBLIB for the job, then any STEPLIB for the step. The first library that contains a member named SORT is used, and that program is loaded and executed. So the "installation" of DFSORT really means: the load module(s) are in one or more of those libraries. If your site uses a third-party sort (e.g. Syncsort), the same name SORT might point to that product's program if its library is earlier in the search order. The messages in SYSOUT (e.g. ICE for DFSORT) tell you which product actually ran.

What Is Installed?

A typical DFSORT installation includes:

• Load modules — SORT (or ICEMAN), ICETOOL, ICEGENER, and supporting modules. These are the executable programs that run when you invoke PGM=SORT, PGM=ICETOOL, etc.
• Libraries — The load library (or libraries) that contain these modules. They may be in a system LIB (e.g. SYS1.LINKLIB or a product library) or in a user library that is in the link-list or specified via JOBLIB/STEPLIB.
• Optional — Some installations include sample JCL, sample control statements, or documentation in separate datasets. These are for reference; they are not required for DFSORT to run.

IBM supplies DFSORT as part of z/OS or as a licensed program product. The exact packaging and naming can vary by release. Your site may also have a license for a different sort product (e.g. Syncsort); in that case, "installation" might mean that product is in the load library and possibly aliased as SORT or ICEMAN.

What Application Programmers Need to Know

For day-to-day use you need to know:

• How to invoke it — EXEC PGM=SORT (or PGM=ICEMAN), with SYSOUT, SORTIN, SORTOUT, and SYSIN. Optional SORTWKnn if your shop requires explicit work datasets.
• That it is available — If your job fails with "program not found" or an 806 (module not found), the load library or concatenation may be wrong. That is usually a system or support task to fix (e.g. add the product library to the link-list or tell you to use a specific JOBLIB).
• Control statement syntax — SORT FIELDS, MERGE, INCLUDE, OMIT, INREC, OUTREC, OUTFIL, SUM, OPTION, etc. This is independent of installation; you learn it from documentation and tutorials.

You generally do not need to know where the load module lives on disk, the exact product level, or the SMP/E install history—unless you are debugging a "wrong program" or version issue.

JOBLIB and STEPLIB

If your site has more than one sort product or more than one level of DFSORT, JOBLIB or STEPLIB can be used to point to a specific load library. For example, you might add a STEPLIB before the EXEC so that the step uses a particular library first. That way you can force the use of a given product or level without changing the system link-list. Only system programmers or your support team would typically define which library to use; you might be given a procedure or JCL that already includes the right STEPLIB.

Explain It Like I'm Five

Installing DFSORT is like putting a big sorting machine in the building. The people who run the building (system programmers) bring in the machine and plug it in so that when anyone asks for "the SORT machine," the right one is there. You (the application programmer) don't install the machine—you just press the button (run JCL with PGM=SORT) and give it your pile of cards (SORTIN) and instructions (SYSIN). As long as the machine is installed and turned on, you can use it. If the button doesn't work (program not found), you ask the building people to fix it.

Exercises

1. Who is responsible for installing DFSORT at your site? What is your role as an application programmer?
2. How does the system find the program when you specify PGM=SORT?
3. What would you do if your job failed with "program SORT not found"?
4. What is the purpose of STEPLIB when running a sort step?