A fix is available
APAR status
Closed as program error.
Error description
During periods where CSM fixed storage is constrained, TCP outbound processing fails during send processing trying to extend BGRPs. The BGRP is used for outbound blocking and allocation attempts for new BGRPs fails when CSM fixed is constrained. This causes BGRPs to be leaked in ECSA, but this leak also causes 32k fixed CSM dataspace buffers associated with these leaked BGRPs to accumulate. This accumulation of CSM fixed storage causes CSM to remained constrained for long periods of time. When CSM becomes constrained all outbound and inbound packet operations can fail, resulting in degraded performance and eventually connection failures. Running in a constrained mode for a lengthy period of time will result in total failure of the stack operations and most likely will result in an IPL. Additional Symptom(s) Search Keyword(s): BGRP CSM fixed 32k dataspace CSM64001
Local fix
enable segmentation offload or increase CSM fixed storage if real memory is not a factor Verification steps: The orphaned BGRP control blocks in ECSA will have the following: - offset x'14' will have x'66' - offset x'CC' will be an address to an SKMB/SKDB that points to the orphaned CSM 32k dataspace fixed buffer the SPAC at offset x'F0' into the BGRP has a zero SPAC_WE_NEXT (offset 4) value - There will be a high number of CSM 32k DATASPACE buffers with a CSM Monitor ID value of x'92' (ifBlockPack) owned by TCP/IP. - CSM storage displays will show CSM fixed storage owned by TCPIP increasing as well as CSM constrained message IVT5592I and IVT5565I periodically - SYSTCPIP VTAMDATA exception records: " !Storage Error - Msg_Wont_Fit" and " !Storage Error on BGRP" will be seen
Problem summary
**************************************************************** * USERS AFFECTED: All users of the IBM Communications Server * * for z/OS Version 1 Release(s) 12 and 13 IP * **************************************************************** * PROBLEM DESCRIPTION: CSM FIXED ECSA and dataspace storage * * leak when CSM is in the constrained or * * critical state * **************************************************************** * RECOMMENDATION: * **************************************************************** Fixed CSM ECSA and dataspace storage leak when CSM is in the constrained or critical state. A blocking algorithm is used to acheive optimal performance when sending packets outbound over an OSA device. The blocking process uses a control structure that resides in fixed CSM ECSA and a 32K buffer that resides in fixed CSM dataspace. When TCP connections are streaming large amounts of data outbound it can result in the need for multiple blocking control structures and 32K buffers. The allocation of additional control structures and 32K buffers fail when CSM is in a constrained or critical state for fixed storage. When an allocation failure for the control structure or 32K buffer fails and two or more already exist for the device, the last control structure and 32K buffer successfully allocated for the device will be leaked. Enabling segmentation offload on the IPCONFIG, IPCONFIG6, or GLOBALCONFIG profile statements can be used to optimize the CPU utilization for outbound TCP traffic and prevents this problem from occurring. +-------------------------------------------------------------+ + Please check our Communications Server for OS/390 homepages + + for common networking tips and fixes. The URL for these + + homepages can be found in Informational APAR II11334. + +-------------------------------------------------------------+
Problem conclusion
EZBIFBP1 has been amended to handle the allocation failure of a blocking algorithm control structure or 32K buffer. * Cross Reference between External and Internal Names
Temporary fix
********* * HIPER * *********
Comments
APAR Information
APAR number
PM81034
Reported component name
TCP/IP V3 MVS
Reported component ID
5655HAL00
Reported release
1D0
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt
Submitted date
2013-01-21
Closed date
2013-02-14
Last modified date
2013-05-06
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK91704 UK91706
Modules/Macros
EZBIFBP1
Fix information
Fixed component name
TCP/IP V3 MVS
Fixed component ID
5655HAL00
Applicable component levels
Fix is available
Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.
[{"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"SG19M","label":"APARs - z\/OS environment"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"1D0","Edition":"","Line of Business":{"code":"","label":""}},{"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"SSCY4DZ","label":"DO NOT USE"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"1D0","Edition":"","Line of Business":{"code":"","label":""}}]
Document Information
Modified date:
06 May 2013