Non-VSAM data sets are the most common type of data set found on z/OS. They are a collection of fixed-length or variable-length records, which can be physically stored in groups (blocks), or individually. There are several different types of non-VSAM data sets:
NON-VSAM:--
---> Physical Sequential (PS)
---> Partition Organized (PO)
---> Partitioned Dataset (PDS)
---> Partition dataset Extended (PDSE)
Physical Sequential (PS) Dataset
- A simple file with records stored in the order that they are written.
- New records are appended to the end of the data set.
- Maximum extents for PS is 16 for 1 volume.
- PS can span up to 59 volumes so 59 x 16 = 944extents.
Physical Sequential – Extended
- Extended-format data sets have a maximum of 123 extents on each volume.
- PS - E can span up to 59 volumes so 59 x 123 = 7257extents.
- PS - E data sets can go beyond the 65,535 tracks.
Partitioned Dataset (PDS) Dataset
- A directory of sequentially organized members, each of which contain sequentially organized data.
- Each individual member can be accessed without searching the entire data set.
- It contains Members into the Datasets.
- Members are calculated with the formula 6(n) – 1. (directory blocks).
- Maximum extents for PDS is 16. it cannot go beyond.
Advantages of PDS :-
- Grouping of related datasets under a single name.
- Small datasets which are smaller than track can be allocated.
- Multiple PDS datasets can be concatenated.
- can be created easily with ISPF or JCL.
Disadvantages of PDS:-
- Wasted space.
- Limited directory size.
- Lengthy directory searches
Partition Dataset Extended (PDSE) Dataset
- A PDS which does not have a fixed size directory and can reuse deleted space.
- They also have better facilities for data sharing.
- PDSE stores programs as program object.
- No limitations to 16 extents, it can go up to 123 extends in 1 volume.
- 1 volume can have 65535 tracks and beyond.
- The addressing limit is 522236 members.
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