Clem, the answer comes down to how the SMS environment was set up. At the last place I worked your JCL example might have worked but you may not have gotten what you expected for the dataset attributes. If I recall from the SMS set up your allocation would have been fixed block 80 byte records with a small space allocation. If that is what you wanted then great.
As was mentioned the default for things like RECFM and LRECL may not be what you want for your dataset. The vast majority of the time I coded RECFM, LRECL and SPACE in my JCL. So, it's back to the dreaded "it depends" answer. Paul -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of Paul Gilmartin Sent: Saturday, August 2, 2025 10:13 AM To: [email protected] Subject: Re: Modern JCL for new Data Set Allocation On Sun, 3 Aug 2025 00:13:01 +1000, Clement Clarke wrote: > ... >"With SMS, the JCL becomes much cleaner. The system handles the >allocation details based on its policy. A ... > I see wishful thinking in "The system ... its policy." It's not the system but the data administrator who determines policies. And the end user or department is still burdened with choosing a class with suitable details. And the need for multiple classes for combinations of DCB attributes. Pre-SMS, I worked with a site that required a paper request for any permanently cataloged data set. I have long wished for a UNIX-like disposition status meaning, "NEW if possible; otherwise overwrite it. I can simulate that wit an additional DD statement. And for exponentially increasing extent sizes, which might mitigate space lost by over-allocation. UNIX has per-user space quotas with a performance cost; MVS addressed the need by supporting a separate filesystem for each user, again with over-allocation penalty. How about a scheme where a job could wait until needed temporary space became available? -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
