(This is an answer also to Vernooij.) Please consider what You do manually when the space is to small (e g B37 etc.), or You just is unsure: You try a bigger allocation, maybe also extend (or reduce) the secondary amount. And repeat. Often many times. Would it be a problem if this (more or less) is automated ? Hm ?
Technically I suppose it's solved by an initial "virtual" allocation filling a buffer in memory. Then a disk allocation is done at a threshold with e g 5 cyl. If that is not enough, add 4 times the amount, 20 cyl. Repeat this until finish. Release unused space (from the last add). This is just an example, it can be done much more sophisticated by the OS. And the limit of allocation should be set by userid or datasetname properly. Or maybe by a (e g) LIMIT= keyword. (I'm using the JCL case as an illustrative example, it should of course be general system interface.) Regards, Thomas Berg _________________________________________ Thomas Berg Specialist A M SWEDBANK > -----Ursprungligt meddelande----- > Från: IBM Mainframe Discussion List [mailto:[email protected]] För R.S. > Skickat: den 13 februari 2012 14:49 > Till: [email protected] > Ämne: Re: SV: Archaic allocation in JCL (Was: Physical record size query) > > W dniu 2012-02-13 14:28, Thomas Berg pisze: > [...] > > With SPACE=ANY, the needed space is allocated and extended during the > execution. > > So You don't do any "preallocation" of a specified amount of space. > > Thomas, > Your idea is worth discussion, but not your requirement is off target. > It is not JCL problem, it is z/OS problem. To fill the requirement the > sapce should be allocated ad hoc, cluster after cluster (*). That > requires total VTOC revolution. > > BTW: Idea of space extents is maybe archaic, but I wouldn't consider it > worse. It's different and reruires different approach and tools. > > > (*) Cluster - in this case the smallest addressable amount of disk > storage. For 3390-3 it would be 1 trk, for NTFS disk in my PC it would > be 4kB, for old FAT format of 2GB partition it was 32kB, for EAS on EAV > device it is 21 CYL. > -- > Radoslaw Skorupka > Lodz, Poland ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
