开云体育

Hi :)

Thank you all.

I was able to verify what happens inside the directory block by creating my own uncompressed 3390 disk and inspecting it with an hexadecimal editor.

PDS Directory block

I was able to confirm the "end marker” inside the 254 bytes for directory entires. That end marker takes 8 bytes, all Bytes 0xFF, ie. 0xFFFFFFFFFFFFFFFF.

I also found out that:

• when creating a PDS member using with JCL DD, it uses the minimal 12-Bytes-long directory entries, so it fits 20 members created by JCL DD.
• when creating PDS members using ISPF (M.1.2 or 2), it uses 42-Bytes-long directory entries, so it fits 5 members created via ISPF.

PDS Member records

Between the directory block and the first member, there is a 16-Bytes-long separator (END marker?).

eg.

00 00 00 02 02 00 00 00 00 00 00 02 03 00 05 A0
             |                       |
             |                       '- First record of member 1 (as in TTR)
             '- Last record of Directory blocks area (as in TTR)

There is also a 16-Bytes-long separator between each member (EOF marker?)

eg.

00 00 00 02 04 00 00 00 00 00 00 02 05 00 05 A0
             |                       |
             |                       '- First record of next member (as in TTR)
             '- Last record of previous member (as in TTR)

And after the last member

00 00 00 02 2C 00 00 00 FF FF FF FF FF FF FF FF
             |
             |
             '- Last record of last member (as in TTR)

Number of records per member

What I still cannot understand is the number of records per member. I can see that the space is available in the track.

Do you know where should I look?

---

Kind Regards

Sergio Lindo Mansilla