The original question was if it is possible to calculate the maximum number of directory blocks with VTOC information. The answer is no, the number cannot be calculated from any information from the VTOC or any other source, unless the directory fills the whole first extent, which is probably not the meaning of "maximum" the OP intended. Some code somewhere has to read all the blocks and count them.
It would be nice if IBM had decided 45 years ago to store the number of directory blocks in the Format 1 DSCB somewhere, but that could easily be a three-byte number, even with early S/360 DASD, and they may have felt that there weren't enough spare bytes in the F1 for that. And with EAV it could be a nine-byte number. There are many other aspects of PDSes that seem now to have been non-optimally designed, but they weren't seen that way 45 years ago. Bill Fairchild Rocket Software -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Ted MacNEIL Sent: Thursday, July 22, 2010 11:04 AM To: IBM-MAIN@bama.ua.edu Subject: Re: Calculate maximum directory blocks of PDS >This value can be accessed using LISTDSI but I don't want to create TSO/ISPF environment. You don't need ISPF to use LISTDSI. Just TSO/REXX. - I'm a SuperHero with neither powers, nor motivation! Kimota! ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
