From: hobbitt [email protected] Date: Fri, 4 Feb 2011 08:43:48 -0800 (PST) Local: Fri, Feb 4 2011 11:43 am
> On Feb 1, 10:41 pm, [email protected] (J R) wrote: > > The JCL User's Guide is more specific on this. It explicitly states: > > "if you code ROUND as the last subparameter in the SPACE parameter, the > > system allocates the smallest number of cylinders needed to contain the > > request." > > "Cylinder allocation (and therefore ROUND used with average block or > > average record) allows faster input/output of sequential data sets than > > does track allocation." > > "If you request space in terms of average block length, the system will > > compute and allocate the smallest number of tracks (or cylinders if ROUND > > is specified)" > > "if you specify the secondary quantity in cylinders, in blocks, or in > > records with the ROUND subparameter, then the secondary space allocated to > > the data set starts at the beginning of a cylinder." > Thanks, J R - I've gotten used to only checking the Reference and not > the User guide, so I didn't see that <thwack on the head>. The > section on secondary allocations has this statement: > "[...] if you specify [...] the ROUND subparameter, then the secondary > space allocated to the data set starts at the beginning of a > cylinder." > But I don't see any similar explicit declaration about primary space > boundaries. > ++hobbitt I don't know why they spelled it out for secondary allocation and not primary allocation. They didn't neeed to do it for either. Cylinder allocation means whole cylinders. Whole cylinders start on cylinder boundaries. ROUND requests the smallest cylinder allocation that has at least the amount of space requested by other terminology. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
