A fix is available
APAR status
Closed as program error.
Error description
When the ABEND0C4 occurs, the instruction at x'F24' into ISTTSCND is attempting to load the halfword value AUNCB_XID_MAXPIU into GPR7, using the value in GPR5 as the base register for the control block supposedly containing the field AUNCB_XID_MAXPIU, which is at offset x'3A6' into the AUNCB. The problem is that GPR5 points to an AHNCB, not an AUNCB, and an AHNCB is only x'1F8' bytes long. Therefore, since offset x'3a6' is past the end of that AHNCB, the ABEND0C4 results when the load instruction is executed.
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All using Enterprise Extender connections. * **************************************************************** * PROBLEM DESCRIPTION: ABEND0C4 occurs in module * * ISTTSCND immediately after a * * path switch. * **************************************************************** * RECOMMENDATION: * **************************************************************** Sample Configuration: <-------CNR00005-------> -------- -------- - - =======EE======= - - -VTAM A- -VTAM B- - - ======AHHC====== - - -------- -------- The problem is summarized as follows: 1) An HPR pipe is established between VTAM A to VTAM B over an EE connection. 2) VTAM A transmits a packet over CNR00005 to VTAM B. 3) As data is transmitted from RTP, the TSCB_RPNCB field is filled in by the local RTP endpoint with the internal address of the RPNCB control block. 4) The TSCB is built and forwarded to the EE TCP/IP stack for transmission. 5) While the TCP/IP stack is sending the HPR packet, VTAM B initiates and completes a path switch for this pipe. 6) At this point, the HPR pipe path switched from an EE connection to an AHHC connection. 7) On VTAM A, the outstanding HPR packet is returned to VTAM from the EE TCP/IP stack. 8) Module ISTTSCND processed the packet and located the RPNCB control block from the TSCB_RPNCB field. 9) Segment CHECKMTU, is referencing various AUNCB fields (i.e. AUNCB_MTU_SIZE, AUNCB_XID_MAXPIU) which are associated with EE connections. 10) The AUNCB is based on the RPNCB_LOCAL_NCB_PTR. The RPNCB_LOCAL_NCB_PTR is now pointing to an AHNCB control block 11) The AHNCB represents the AHHC connection. Since the AHNCB is not as large as the AUNCB, an ABEND0C4 occurred when referencing these fields.
Problem conclusion
ISTTSCND - Corrected segment CHECKMTU to verify the RPNCB_LOCAL_NCB_PTR is still referencing an AUNCB control block when a packet is returned back to VTAM. ISTAUCLA - Included for maintenance purposes.
Temporary fix
********* * HIPER * *********
Comments
APAR Information
APAR number
OA36401
Reported component name
VTAM V4 MVS/ESA
Reported component ID
569511701
Reported release
1C0
Status
CLOSED PER
PE
NoPE
HIPER
YesHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2011-05-04
Closed date
2011-05-18
Last modified date
2011-08-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UA60444 UA60445
Modules/Macros
ISTAUCLA ISTTSCND
Fix information
Fixed component name
VTAM V4 MVS/ESA
Fixed component ID
569511701
Applicable component levels
Fix is available
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Document Information
Modified date:
01 August 2011