CICS startup hangs waiting on DCCOCPR when the USS option is enabled after CICS upgrade

Products

• Datacom
• DATACOM - AD
• Datacom/AD
• Datacom/DB

Issue/Introduction

Upgrading to new release of CICS.

• When the CICS USS option is enabled, the CICS startup hangs waiting on DCCOCPR. USS is enabled by specifying the USSHOME parameter in the CICS DFHSIT.
• When the CICS USS option is not enabled the CICS region starts, or when DCCOCPR is disabled, the CICS regions also starts.

Environment

Release: All supported releases.

Cause

This is due to the CPLT task waiting for an open TCBs to become available. The USS option takes up one open TCB so if there are insufficient open TCBs defined the CPLT task will hang. Confirm this by looking at a CICS SVC dump and checking if the CPLT task waiting on resource DISPATCH OPENPOOL. 

Follow this procedure to analyse the dump with IPCS:

1. Issue this command in IPCS to format the CICS control blocks: 
   VERBEXIT DFHPD670 'JOB=CURRENT,KE=3,DS=1,TR=3'You also need the CTS420.SDFHLINK in the STEPLIB.
2. Use the correct DFHPDxxx for the release of CICS. CICS TS 4.2 is CICS 6.7 so use DFHPD670. DFHPD650 is for CICS TS 3.2. 
3. Look for 'KE_TASK Summary' in the report and search for the CPLT task: KE_NUM KE_TASK STATUS TCA_ADDR TRAN_# TRANSID DS_TASK KE_KTCB ERROR 0001 164EC000 KTCB Step 00000000 00000000 16530038 ....0021 166EF450 Not Running 00000000 166B2C80 165331B8 
4. See above CPLT is task 0020 with an address of 166E0630.
5. 0020 166E0630 Not Running 0004C080 00008 CPLT 166B2080 165331B8 <-------
6. 0002 164EC630 KTCB QR 00000000 16519F00 165331B8 
7.  
8. ===KE: Kernel Domain KE_TASK Summary 
9. Now find 'DS: TASKS SUMMARY' and look in the KE_TASK column for address 166E0630: DS_TOKEN KE_TASK T S F P TT RESOURCE RESOURCE_NAME W TIME OF TIMEOUT00860003 166A3630 S S N N - ICMIDNTE DFHAPTIM S 06:13:56.605 - 01000003 166E0630 S S P N - DISPATCH OPENPOOL S 06:14:03.079 - <-------  
10. This shows the task is waiting on resource DISPATCH OPENPOOL 
11. 008E0003 177C6800 S S N N - ICEXPIRY DFHAPTIX S 06:15:56.238 - 
12. TYPE SUSPEND DUE 
13. ==DS: TASKS SUMMARY

Resolution

Increase the value for the MAXOPENTCBS parameter in the CICS DFHSIT. 

Alternatively, specify MAXOPENTCBS in the JCL in the PARM paramerter of the EXEC statement or in the SYSIN data set of the CICS startup.