The minimum size for any type of sequential data set that contains data is one track, which is about 56␠000 bytes. You can create a data set that has no space. The purpose for such a data set might be to serve as a model for data set attributes with the LIKE parameter on DD statements. Another purpose might be to allow reading before the data set contains data. For example you might give the data set a secondary space amount such as with SPACE=(CYL,(0,5)).