A fix is available
APAR status
Closed as program error.
Error description
Intermittently the MQ CHIN will experience name resolver errors due to the SYSTCPD DD not being loaded based on its PROC. GetHostByName calls can fail with errors such as GetHostByName Failed: RetVal = -1, RC = 1, Reason = 0x78981005 GetHostByName Ended: year/mm/dd hh:mm:ss.subsec - The local TCP/IP dataset unexpectedly is /etc/resolv.conf instead of the reference set using SYSTCPD DD. As well, the caller API is LE C Sockets instead of USS (Unix System Services) - In the instances where resolution is successful, the caller API is USS. Resolution will complete successfully if the MQ subsystem is recycled. Hursley Change Team and CommServer find that, as there are two types of API mode (LE and USS) the first type of call to be used sets the affinity for any subsequent calls within the address space. - If the first type of call is not through USS then the PrliCICS flag that re-enables the check for //DD:SYSTCPD is ignored. - Code change may include a dummy USS-based DNS lookup during CHINIT initialization to ensure that MQ explicitly establishes affinity to the USS API
Local fix
Recycle MQ CHIN
Problem summary
**************************************************************** * USERS AFFECTED: All users of IBM MQ for z/OS Version 9 * * Release 0 Modification 0 and Release 1 * * Modification 0. * **************************************************************** * PROBLEM DESCRIPTION: Occasionally the SYSTCPD or SYSTCPDD * * card is being ignored on chinit startup * * resulting in failed DNS resolver * * calls. * **************************************************************** A race condition between different tasks on the same process during chinit startup occasionally results in the process not being treated as a USS caller. In this case the DD cards SYSTCPD or SYSTCPDD are being ignored and can result in failed DNS resolver calls.
Problem conclusion
The race condition has been removed thereby ensuring that the process in question is always correctly identified as a USS caller.
Temporary fix
Comments
APAR Information
APAR number
PH13517
Reported component name
IBM MQ Z/OS V9
Reported component ID
5655MQ900
Reported release
000
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-06-18
Closed date
2019-08-27
Last modified date
2019-10-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI64985 UI64986
Modules/Macros
CSQXPENT
Fix information
Fixed component name
IBM MQ Z/OS V9
Fixed component ID
5655MQ900
Applicable component levels
Fix is available
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Document Information
Modified date:
01 October 2019