A fix is available
APAR status
Closed as program error.
Error description
CICS abends after taking an 0C1 due to a wild branch: DFHDS0001 An abend (code 0C1/AKEA) has occurred at offset X'FFFF' in module DFHDSTCB. Two CEMT tasks are entered at almost the same time on the MVS console. The first CEMT request causes a CATA task to be created to autoinstall the console TCTTE. The 2nd console input finds that a console TCTTE is being autoinstalled so it remains on a queue to be checked later every time the TCP task runs. The problem happens when the CATA task does a GETMAIN for AI-TIOA storage and suspends on the SMLOCK. This causes the CATA task to lose control of the QR TCB. This allows the TCP task to come back to life and try again to process the 2nd console input. The TCP task finds that the console TCTTE has now been autoinstalled by the first request and now it tries to GETMAIN TIOA storage but suspends on the SMLOCK. The CATA task wakes back up after getting the SMLOCK, and attaches the first CEMT task. But when the TCP task wakes up after getting the SMLOCK, it proceeds to attach a CEMT too and is successful. But both CEMT tasks are now associated with the same console TCTTE. There is code in DFHZATT that looks like it would prevent this problem but it is only executed for VTAM terminals. Additional Symptom(s) Search Keyword(s): DFHZATA2 DFHZCNA TCTE_TRANNUM abend0C1 abendS0C1 S0C1 unpredictable results
Local fix
Problem summary
**************************************************************** * USERS AFFECTED: All CICS users. * **************************************************************** * PROBLEM DESCRIPTION: CICS receives several CEMT commands * * issued in quick succession from a * * console. Two of the commands get given * * the same console name and are running * * at the same time. An 0C1 occurs. * **************************************************************** There is a window in DFHZATA2 console attach where console autoinstall can create a TCTTE but suspend and lose control of the QR TCB. This allows TCP to run again and check the console deferred queue. If TCP finds another command issued from the same console it will use the TCTTE it created for the suspended command. CSTP will continue attaching both transactions, but they will both be running on the same console/terminal which should not be possible. This resulted in a corruption causing an 0C1 abend.
Problem conclusion
DFHZCNA and DFHZATA2 have been changed to check if there is an attach pending on the TCTTE, and to defer the processing of the command if there is. The CICS Documentation will be updated for TCTTE - TCT terminal entry in the DATA AREAS section Table 1. (A4) BIT(8) 1 TCTTEDII DYNAMIC INSTALL indicators (A4) 1... .... TCTTEDAP Pending DYNAMIC ADD (A4) .1.. .... TCTTEDDP Requires deleting (A4) ..1.. .... TCTEATTP ATTACH in progress (A4) ...1 .... * Reserved
Temporary fix
Comments
APAR Information
APAR number
PH61179
Reported component name
CICS TS Z/OS V6
Reported component ID
5655YA100
Reported release
400
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2024-05-01
Closed date
2024-06-24
Last modified date
2024-07-01
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
UI97445
Modules/Macros
DFHTCTTE DFHTCTZE DFHZATA2 DFHZCNA
Fix information
Fixed component name
CICS TS Z/OS V6
Fixed component ID
5655YA100
Applicable component levels
R400 PSY UI97445
UP24/06/27 P F406
Fix is available
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Document Information
Modified date:
02 July 2024