How many Cylinders does it will occupy?

Husna · New User Joined: 02 Jun 2006 Posts: 49

Hi all,

I am new to Mainframes?. Could you please any one of you let me know. How many Cylinders does it will occupy for the following query?

SPACE=(CYL,(1,2))

sandhyaragav · New User Joined: 05 Apr 2006 Posts: 14

No.of cylinders would be 1+(16*2) = 33 cyl

Sandhya

Husna · New User Joined: 02 Jun 2006 Posts: 49

Hi Sandhya,

Thanks for your quick response. As per my knowledge? Up to 15 extends of secondary space (in our example it is 2) will be allotted, If space is not sufficient.

Could you please let me? How many extends will be allotted for the same (15 or 16)?

One more thing, I would like to ask you? Whether this extends will be starts from 0 or 1?

Awaiting your reply.

Rupesh.Kothari · Member of the Month Joined: 27 Apr 2005 Posts: 463

Hi,

Husna · New User Joined: 02 Jun 2006 Posts: 49

Hi Rupesh,

Thanks a lot.

So, final answer is... No.of cylinders would be 1+(15*2) = 31 cylinders.

Marso · Posted: Mon Jun 05, 2006 7:30 pm

And don't forget, you can write:
SPACE=(CYL,(1,2),RLSE)
which means extra space will be released when the file is closed.

According to the book: "The system releases space only if the data set is open for output and the last operation was a write."

I think it can release part of a cylinder (which means you can finish with a file which is 6 cyl and 10 tracks, for example).

mmwife · Super Moderator Joined: 30 May 2003 Posts: 1592

And also don't forget that the sys may use up to 5 extents to satisfy your primary alloc. In that case you will only have 11 2ndary ext available.

That rule wouldn't apply in this case (1 CYL primary) because 1 CYL is the smallest unit of alloc. If it were changed to (TRK,(20,40)) the rule would apply.

prasadvrk · Posted: Tue Jun 06, 2006 4:41 pm

All,

I think it wont be amiss to mention here that 1 primary and 122 secondary extents are allocated to VSAM datasets.

Any one correct me If I am wrong.