Problem: A VTAM APPC or TCP/IP conversation failed during or after allocation and is unavailable for use.
Symptom: VTAM or TCP/IP returns a resource unavailable condition along with the appropriate diagnostic reason code and message. A DSNL500 or DSNL511 (conversation failed) message is sent to the console for the first failure to a location for a specific logical unit (LU) mode or TCP/IP address. All other threads detecting a failure from that LU mode or IP address are suppressed until communications to that LU using that mode are successful.
DB2 returns messages DSNL501I and DSNL502I. Message DSNL501I usually means that the other subsystem is not up.
When the error is detected, it is reported by a console message and the application receives an SQL return code. For DB2 private protocol access, SQLCODE -904 (SQLSTATE '57011') is returned with resource type 1001, 1002, or 1003. The resource name in the SQLCA contains VTAM return codes such as RTNCD, FDBK2, RCPRI, and RCSEC, and any SNA SENSE information. See VTAM for MVS/ESA Messages and Codes for more information.
If you use application directed access or DRDA as the database protocols, SQLCODE -30080 is returned to the application. The SQLCA contains the VTAM diagnostic information, which contains only the RCPRI and RCSEC codes. For SNA communications errors, SQLCODE -30080 is returned. For TCP/IP connections, SQLCODE -30081 is returned. See DB2 Codesfor more information about those SQL return codes.
The application can choose to request rollback or commit. Commit or rollback processing deallocates all but the first conversation between the allied thread and the remote database access thread. A commit or rollback message is sent over this remaining conversation.
Errors during the conversation's deallocation process are reported through messages, but do not stop the commit or rollback processing. If the conversation used for the commit or roll back message fails, the error is reported. If the error occurred during a commit process, the commit process continues, provided the remote database access was read only; otherwise the commit process is rolled back.
System programmer action: The system programmer needs to review the VTAM or TCP/IP return codes and might need to discuss the problem with a communications expert. Many VTAM or TCP/IP errors, besides the error of an inactive remote LU or TCP/IP errors, require a person who has a knowledge of VTAM or TCP/IP and the network configuration to diagnose them.
Operator action: Correct the cause of the unavailable resource condition by taking action required by the diagnostic messages appearing on the console.