In SAS on z/OS, extremely high volumes of FTP connections executed in a short period can cause SAS to stop after an unpredictable number of transfers. No warning or error messages are written to the SAS log, and the SAS job becomes unresponsive and must be cancelled manually when this issue occurs.

If the task appears to load and unload TKITCP, the issue might be related to the TCP ephemeral ports being unavailable. 

Workaround

A possible workaround is to set the following SAS environment variable in the SAS //TKMVSENV file for the SAS session: TCP_EPH_MAP_ENABLED=0

Note the following effects of this workaround:

• This setting affects all SAS TCP-based traffic, not only the FTP access method.
• With this environment variable enabled, z/OS provides ephemeral ports from the full available range.

See SAS Note 58546, "Controlling which TCP/IP ephemeral ports SAS^®9 uses under z/OS" for additional information.