IBM Mainframe Forum

Hello,
I need information for extented sequential file like how is extended ps allocated,how many extents would it take,space calculation for the same etc.
Also if anyone can provide a doc or suggest a manual which has details about space calculation for datasets that would be of great help.
Thanks.

This a link to the device type 3390 capacities manual. Based on BLKSIZE and record count, you can determine how many track/cyls are required. http://publibz.boulder.ibm.com/cgi-bin/ ... 1001/B.1.2

Are you asking about Extended Format datasets or simply datasets with multiple extents? The secondary quantity in the SPACE=(type,(prim,sec)) will allow your file to take extents.

Hi bill,thanks for the info..Can u tell me how the extents are allocated for any dataset? Also how to calulate the free space and percentage of space used by a dataset(PS,PDS) ?

storage wrote:Can u tell me how the extents are allocated for any dataset?

When the primary space is used up, the secondary amount will be allocated.

storage wrote:Also how to calulate the free space and percentage of space used by a dataset(PS,PDS) ?

The dataset's entry in the VTOC, called the DSCB, knows the total space allocated and the last track that contains data. The difference is the free space. You can calculate the percentage from the dataset info on the ISPF display on option 3.2.

I know that once primary is utilised secondary would be used..Lets take an example that there is a PS with primary 15 cyls and sec 20 cyls,then how will the space be allocated?

In the most simple scenario, once the primary of 15 cyls is used up, the secondary amount (20 cyls) will be obtained up to 15 times. Assuming free space remains on the volume.