Mainframe programmers are problem-solvers. In right this moment’s giant, complicated 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 often desires solutions proper now:
- What does this dataset appear to be?
- What are its traits?
- How a lot house does it occupy?
- When was it created and final referenced?
For a single dataset, this kind of info can often 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 acquire detailed knowledge for every dataset, probably maintain 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 perform permits the programmer to simply acquire all types of details about a z/OS dataset.
LISTDSI returns knowledge in effectively 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 listing of dataset names, LISTDSI variables like SYSALLOC and SYSUSED could be accrued to maintain a working whole of disk house. 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 perform and should run in a TSO deal with house. That is often not an issue, nevertheless, because it’s potential to run TSO in batch just by specifying PGM=IKJEFT01.
The only format of LISTDSI is just a REXX perform specifying the dataset identify, for instance:
x = LISTDSI(the-dataset)
the place ‘the-dataset’ is a variable containing the one dataset identify for which we wish info.
The variable ‘x’, the perform code, is important as a result of LISTDSI should be referred to as as a REXX perform. A zero perform 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’ – similar to 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-obligatory 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 identify within the LISTDSI name to return additional info, together with listing block counts and SMS class names.
Crucial 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 Methods Companies information, and era dataset names should be absolutely specified (no relative GDGs). For VSAM datasets, solely a restricted subset of data is returned (SYSVOLUME, SYSUNIT, and SYSDSORG).
It’s potential these drawbacks shall be eliminated in a future z/OS launch. Even with these limitations, nevertheless, 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 gives a fast manner for the programmer – dealing with 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 exhibits a easy REXX exec that shows among 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 offers mainframe groups a quick, versatile technique to extract important dataset particulars utilizing acquainted REXX constructs – making it simpler to reply questions, spot points, and maintain storage info flowing when it issues most.
To go even additional and acquire deeper visibility, automation, and management throughout your storage atmosphere, be taught extra about how Syncsort™ Storage Administration helps simplify and optimize z/OS storage operations.
