Gen TISRVMSL gets many "DID NOT RECEIVE FULL CFB HEADER; SOCKET CLOSED" errors

Products

• Gen
• Gen - Run Time Distributed

Issue/Introduction

Gen 8.6 Multi Sockets CICS Listener TISRVMSL produces many of these error messages:

TISRVMSL TIML TASK=######## MM/DD/YYYY HH:MM:SS DID NOT RECEIVE FULL CFB HEADER; SOCKET CLOSED
TISRVMSL TIML TASK=######## MM/DD/YYYY HH:MM:SS DID NOT RECEIVE FULL CFB HEADER; SOCKET CLOSED
TISRVMSL TIML TASK=######## MM/DD/YYYY HH:MM:SS DID NOT RECEIVE FULL CFB HEADER; SOCKET CLOSED

Resolution

The message "DID NOT RECEIVE FULL CFB HEADER; SOCKET CLOSED" is produced when the listener receives the buffer (the header part of CFBDATA) from TCP/IP and does not get the entire number of bytes of data.  It could be that the network data transmission is slow and the listener gave up before all of the bytes arrive or if the packets get lost. When the listener does not get the complete number of bytes, it tries for a number of times and then produces the message and closes the socket.

LU19283 is the fix to resolve this issue of TISRVMSL producing excessive CICS log messages which were caused when ping/health/penetration test requests arrive.

Other possible changes to address this issue are increasing the REATIME on the EZACONFG entry for the listener or by setting the values in the TIRSLTMX parameters REATOUTS and REATOUTM. For details refer to Gen 8.6 documentation section "Reference > User Exits > z/OS User Exits > z/OS Middleware User Exits – CICS TCP/IP Direct Connect Exits > TIRSLTMX - CICS Sockets Server Listener TIMEOUT Exit".

Additional Information

LU08295 is a fix to resolve the issue of TISRVMSL producing other excessive CICS log messages that began occurring under z/OS versions 2.5 or higher. For more specific details refer to KB 272692.