Mainframe programmers are problem-solvers. In immediately’s giant, complicated information facilities, we’re usually confronted with ad-hoc questions from administration – questions that echo the outdated Nationwide Enquirer slogan, “Inquiring Minds Need to Know.” And administration normally needs solutions proper now:
- What does this dataset seem 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 an inventory of datasets, although, it’s not so easy. We have to receive detailed information for every dataset, presumably preserve monitor of operating totals, and supply a report.
Why REXX and LISTDSI Are a Pure Match
The REXX programming language is good 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 information in properly over 30 variables that may inform us all the things 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 could be gathered to maintain a operating complete of disk area. Different variables, like SYSEXPIRE and SYSUPDATED, can be utilized to determine potential issues – for instance, disk datasets which have expired or have been modified however not backed up.
Operating LISTDSI in TSO or Batch
LISTDSI is a TSO/E exterior operate and should run in a TSO tackle area. That is normally not an issue, nonetheless, because it’s attainable to run TSO in batch just by specifying PGM=IKJEFT01.
The best format of LISTDSI is solely a REXX operate specifying the dataset title, for instance:
x = LISTDSI(the-dataset)
the place ‘the-dataset’ is a variable containing the only dataset title for which we would like info.
The variable ‘x’, the operate code, is critical 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 information 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. Nevertheless, a number of further parameters can comply with the dataset title 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.
Recognized Limitations to Be Conscious Of
There are, sadly, nonetheless just a few limitations to LISTDSI processing.
No info is returned for tape or Unix Techniques Providers recordsdata, and technology dataset names have to be absolutely specified (no relative GDGs). For VSAM datasets, solely a restricted subset of data is returned (SYSVOLUME, SYSUNIT, and SYSDSORG).
It’s attainable these drawbacks will likely be eliminated in a future z/OS launch. Even with these limitations, nonetheless, LISTDSI is a very easy technique to get detailed details about z/OS datasets.
That info is returned in easy-to-use REXX variables, and offers a fast means for the programmer – dealing with a sudden demand for information – to supply what’s wanted, when it’s wanted, to fulfill these inquiring managerial minds.
Instance: Displaying Key LISTDSI Variables
The determine under exhibits a easy REXX exec that shows a few of the extra fascinating LISTDSI variables for a specified dataset title, together with the date and time the dataset was created:
Turning LISTDSI Output into Operational Perception
LISTDSI offers mainframe groups a quick, versatile technique to extract crucial 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 achieve deeper visibility, automation, and management throughout your storage surroundings, be taught extra about how Syncsort Storage Administration helps simplify and optimize z/OS storage operations.
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