Did you know if you are applying one of the following:
Unicenter TCPaccess Communication Server 6.0SP3
Unicenter TCPaccess FTP Server 6.0 SP1
Unicenter TCPaccess FTP Server 6.1 SP1
you may see the following when running an FTP batch job that does FTP and processing of a GDG in the same job:
550 GDG base already in use
550: The process cannot access the file because it is being used by another process.
This is introduced by TP10272 (TCPaccess 6.0), FT10274 (FTP server 6.0), or FT10273 (FTP Server 6.1).
This is not a 'problem' as such, but a correction of improper GDG handling on the part of FTP. Before this fix, FTP would create a new GDG data set even if another task already had the base GDG enqueued. We have closed that loophole. Correcting this causes the same situation that has existed for regular sequential datasets since inception of the product. If you have any batch jobs that fit this description, they either need to be separated into two jobs or use an IDCAMS with ALTER ... NEWNAME to correct the problem.
A complete description of what is needed can be found in the Users Guide, Chapter 2 under 'Transferring and Using a File in a Single JCL Job' on page 2-65.