Mainframe programmers are problem-solvers. In right this moment’s giant, advanced knowledge facilities, we’re usually confronted with ad-hoc questions from administration – questions that echo the previous Nationwide Enquirer slogan, “Inquiring Minds Wish to Know.” And administration normally desires solutions proper now:
- What does this dataset appear like?
- What are its traits?
- How a lot area does it occupy?
- When was it created and final referenced?
For a single dataset, this form of info can normally be obtained with a look at an ISPF panel or two. For a listing of datasets, although, it’s not so easy. We have to receive detailed knowledge for every dataset, presumably preserve monitor of working totals, and supply a report.
Why REXX and LISTDSI Are a Pure Match
The REXX programming language is right for fixing these types of issues, and the REXX LISTDSI operate permits the programmer to simply receive all types of details about a z/OS dataset.
LISTDSI returns knowledge in nicely over 30 variables that may inform us every part from the dataset’s group and document size to its encryption key label, variety of listing blocks, and SMS class names.
When utilized in a loop to learn an enter record of dataset names, LISTDSI variables like SYSALLOC and SYSUSED will be gathered to maintain a working whole of disk area. Different variables, like SYSEXPIRE and SYSUPDATED, can be utilized to establish potential issues – for instance, disk datasets which have expired or have been modified however not backed up.
Working LISTDSI in TSO or Batch
LISTDSI is a TSO/E exterior operate and should run in a TSO handle area. That is normally not an issue, nevertheless, because it’s attainable to run TSO in batch just by specifying PGM=IKJEFT01.
The best format of LISTDSI is just a REXX operate specifying the dataset identify, for instance:
x = LISTDSI(the-dataset)
the place ‘the-dataset’ is a variable containing the only dataset identify for which we wish info.
The variable ‘x’, the operate code, is important as a result of LISTDSI have to be known as as a REXX operate. A zero operate code signifies success, 4 signifies partial success (some however not all knowledge returned), and 16 signifies a failure.
The precise dataset info is positioned in quite a few predefined REXX variables, all of which start with the characters ‘SYS’ – resembling SYSVOLUME, SYSDSORG, SYSRECFM, and so forth. The contents of those variables can then be written out utilizing REXX ‘SAY’ statements or used for different processing within the exec.
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Non-compulsory Parameters That Return Even Extra Element
By default, LISTDSI merely obtains details about the dataset from the catalog and the amount VTOC. Nonetheless, a number of extra parameters can comply with the dataset identify within the LISTDSI name to return additional info, together with listing block counts and SMS class names.
An important of those parameters are:
- RECALL/NORECALL, which controls whether or not DFSMShsm is allowed to recall datasets from archive throughout LISTDSI processing
- SMSINFO/NOSMSINFO, which returns the category names for SMS-managed datasets.
Identified Limitations to Be Conscious Of
There are, sadly, nonetheless a number of limitations to LISTDSI processing.
No info is returned for tape or Unix Programs Companies recordsdata, and technology dataset names have to be totally specified (no relative GDGs). For VSAM datasets, solely a restricted subset of data is returned (SYSVOLUME, SYSUNIT, and SYSDSORG).
It’s attainable these drawbacks shall be eliminated in a future z/OS launch. Even with these limitations, nevertheless, LISTDSI is a very easy solution to get detailed details about z/OS datasets.
That info is returned in easy-to-use REXX variables, and gives a fast manner for the programmer – going through a sudden demand for knowledge – to supply what’s wanted, when it’s wanted, to fulfill these inquiring managerial minds.
Instance: Displaying Key LISTDSI Variables
The determine under reveals a easy REXX exec that shows a few of the extra attention-grabbing LISTDSI variables for a specified dataset identify, together with the date and time the dataset was created:
Turning LISTDSI Output into Operational Perception
LISTDSI provides mainframe groups a quick, versatile solution to extract important dataset particulars utilizing acquainted REXX constructs – making it simpler to reply questions, spot points, and preserve storage info flowing when it issues most.
To go even additional and acquire deeper visibility, automation, and management throughout your storage setting, be taught extra about how Syncsort Storage Administration helps simplify and optimize z/OS storage operations.
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