A fix is available
APAR status
Closed as program error.
Error description
The final timer expiration for a TCP connection (FINWAIT2 or TIMEWAIT) will cause the use count for the associated control blocks to drop to zero. When this occurs, the EZBTCERF entry point in EZBTCUTL is invoked causing a DUSA expansion. This will cause a 36K block of ECSA storage to be allocated for this processing. When multiple connections are terminated at the same time (such as the shutdown of a server application), the potential exists for all of these to have the final timer expire at the same. If there is resource contention involved in that final processing (such as communication for distributed connections or SMF recording), there can be a large number of these 36K areas generated. This can lead to: - Various ABENDs, typically multiple S4C5/74FF2500 in TCPIP processing. - If ECSALIMIT is configured in TCPIP, EZZ4360I ECSA CONSTRAINED and EZZ4361I ECSA CRITICAL messages could be issued. - If SYSPLEXMONITOR is enabled in TCPIP, this situation can cause the stack to leave the sysplex. This would be accompanied by EZD1973E MULTIPLE TCPIP NONRECOVERABLE ERRORS ARE ADVERSELY AFFECTING SYSPLEX PROCESSING and EZZ9676E SYSPLEX PROBLEM DETECTION CLEANUP HAS SUCCEEDED FOR TCPIP messages.
Local fix
If the stack has left the sysplex, use system monitoring tools to check the levels of ECSA usage and DISPLAY TCPIP,,STOR commands to monitor the amount of ECSA used by TCPIP. Once the usages drop back to normal levels, a VARY TCPIP,,SYSPLEX,JOINGROUP can be issued to allow the stack to rejoin the sysplex.
Problem summary
**************************************************************** * USERS AFFECTED: All users of the IBM Communications Server * * for z/OS Version 1 Release(s) 13 IP * **************************************************************** * PROBLEM DESCRIPTION: Temporary ECSA storage growth occurs * * when TCP connections are freed from * * timer related processing. * **************************************************************** * RECOMMENDATION: * **************************************************************** Temporary ECSA storage growth occurs when TCP connections are freed from timer related processing. The TCP connection control block (TCB) contains a reference count. When the reference count becomes zero a routine is called to perform cleanup processing on the TCB. The module that most frequently performs the reference decrement to zero also contains the clean up routine. The call to the clean up routine is always done as an external call which requires additional dynamic storage. The clean up routine should be called as an internal routine to reduce the dynamic storage requirements. The TCP state timer routines for FINWAIT2 and TIMEWAIT use ECSA for dynamic storage. Timer processing can schedule a large number of FINWAIT2 or TIMEWAIT timer routines that will most likely decrement the reference count to zero, thus causing a temporary increase in ECSA usage. Converting the call to the TCB clean up routine to an internal call will reduce the ECSA usage when a large number of timer routines are scheduled at the same time. +-------------------------------------------------------------+ + 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
EZBTCUTL has been amended to call the TCB clean up routine as an internal call. * Cross Reference between External and Internal Names
Temporary fix
Comments
ž**** PE12/11/14 FIX IN ERROR. SEE APAR PM77118 FOR DESCRIPTION
APAR Information
APAR number
PM71528
Reported component name
TCP/IP V3 MVS
Reported component ID
5655HAL00
Reported release
1D0
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2012-08-24
Closed date
2012-09-20
Last modified date
2012-12-04
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UK82041 PM76819
Modules/Macros
EZBTCUTL TOTCPDS
Fix information
Fixed component name
TCP/IP V3 MVS
Fixed component ID
5655HAL00
Applicable component levels
R1D0 PSY UK82041
UP12/10/31 P F210
Fix is available
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Document Information
Modified date:
04 December 2012