IBM Mainframe Forum

Hi all,
I am just confused with "release" and "compress". It seems space are freed either I use "release" command or "compress" command.
So what's the difference between the two concepts?
Thanks in advance.

"Release" de-allocates unused space from a data set; "compress" does not. Moreover, "compress" only applies to a PDS.

These users thanked the author Akatsukami for the post:

vsevarod (Thu Jun 15, 2017 10:28 am)

Akatsukami wrote:"Release" de-allocates unused space from a data set; "compress" does not. Moreover, "compress" only applies to a PDS.

Thanks, so what did I do when I compressed a PDS?

In a PDS, when you delete a member, the space occupied by the deleted member forms a "hole" in the data set that cannot be used for additional members. When you "compress" a PDS, these "holes" are removed so you can add more members to the data set.

These users thanked the author steve-myers for the post:

vsevarod (Thu Jun 15, 2017 11:45 am)

steve-myers wrote:In a PDS, when you delete a member, the space occupied by the deleted member forms a "hole" in the data set that cannot be used for additional members. When you "compress" a PDS, these "holes" are removed so you can add more members to the data set.

Thanks

Replacing a member in a PDS will normally also leave a hole where the old data was, even if the new data might have fitted in the space occupied by the old member.