IBM Mainframe Forum

hi! Im new to tso/ispf, cobol programming, I just want to ask what will happen if i free or release a partitioned data set tso/ispf using the FREE command? The PDS library is expected to grow. I accidentally hit the F button rather than than the V button. I hope to get a reply soon. thanks

In ISPF, the FREE option (line command F) will release the unused space for the specified dataset. If it grows, you may have to add more space sometime in the future. Personally, I'd run this by the storage team and see if there might be any impact in the future. The TSO FREE command de-allocates the dataset allocation from your TSO session.

There is one important consideration to MrSpock's analysis. Only unused space following the last physical member in the dataset is released. Unused space created by deleting members is not released.

thanks for the replies.

I read somewhere that it's different when the SPACE allocated for the dataset are CYLINDERS?

"Only unused space following the last physical member in the dataset is released"

so that mean I cant add another member to the dataset if it was released?

so that mean I cant add another member to the dataset if it was released

1 - what happened when you tried?
2 - no. another extent will get allocated

whiz18 wrote:thanks for the replies.

I read somewhere that it's different when the SPACE allocated for the dataset are CYLINDERS?

"Only unused space following the last physical member in the dataset is released"

so that mean I cant add another member to the dataset if it was released?

It depends.

• The size of the new member.
• The actual allocation and space available after the space release function completes. I had originally thought to write a much more comprehensive reply, but I canceled that idea after a couple of experiments. There were too many variables to simplify it for a beginner. As NicC says, the system usually can allocate a new extent.

I ran this job --
PDSGAS is a program that analyzes a PDS to "undelete" members, though this run just produces the report. CNVTM is a program to preoare a dataset using carriage control for a PC based word processor, though I usually display the data using Windoze NOTEPAD.

Part of the output from PDSGAS is --"Member" entries marked as GAS represent the space occupied by deleted members. The last member is INVOKE, it starts at TTR 001E01 and ends at TTR 001E03. 0634000001 0634000003 are the disk addresses of the first and last records.

The output from the TSO step is -
The LABEL option tells the LISTDS command to display the contents of the DSCBs for the dataset, in hexadecimal. The C0000001 are codes to indicate the secondary allocation is 1 cylinder. 001E03 4532 The first 6 digits show the TTR of the last record in the dataset. The 4532 is the remaining space on the track, this translates to 17714, but not all of that space can actually be used for data. 8100079D0000079E000E 8101063400000634000E are the extent entries for the dataset. A skilled analyst can quickly deduce the first extent has 2 cylinders, and the second extent has 1 cylinder.

Now, what would happen if I tried the ISPF FREE function for this dataset? Actually, nothing, since part of the second extent contains data.

If I add another member, the system will attempt to use the remainder of the last used track, and then continue using the remaining tracks in the extent.