PH01732: ABEND0C1 IN DB2 INTERNALLY GENERATED CODE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• ABEND0C1 occurred processing a SELECT statement when there is an
  IN or NOT IN statement belong to a big CASE statement.
  From the dump, an indication is the
  Failing instruction text: 0004C0F4 00000018 E340F298
  R14 points to DSNXRBND+882 at PTF level UI54157.
  Additional Keywords: SQLCASE
  

Local fix

• Disable zgencode can bypass the abend
  Please consult IBM Db2z Client Success Team for details
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All Db2 12 for z/OS users of queries that                    *
  * contain a very large CASE statement that                     *
  * includes a boolean expression along with                     *
  * an IN or NOT IN clause, or an IS NULL or                     *
  * IS NOT NULL clause, or a BETWEEN clause.                     *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * An ABEND0C1 rc01 in DSNXRBND can occur                       *
  * when processing a very large CASE                            *
  * statement for a query. The CASE                              *
  * statement includes a WHEN clause that                        *
  * contains a boolean expression with an                        *
  * IN or NOT IN clause, or an IS NULL or                        *
  * IS NOT NULL clause, or a BETWEEN                             *
  * clause where the internal optimized                          *
  * machine generated code will be over                          *
  * 64K in length.                                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * Apply corrective PTF when available                          *
  ****************************************************************
  An ABEND0C1 rc01 can occur in module DSNXRBND when processing a
  very large CASE statement that contains a WHEN clause with a
  boolean expression with an IN or NOT IN clause, or an IS NULL
  or IS NOT NULL clause, or a  BETWEEN clause.  The abend can
  occur if the optimized machine generated code is over 64K in
  length because this causes it to generate an incorrect branch
  instruction.
  
  
  Here is a simple example.
  
  Step ONE. Create a simple Table TBL1.
  
    CREATE TABLE TBL1
       (C1       SMALLINT,
        C2       SMALLINT,
        C3       INT,
        C4       INT,
        C5       CHAR(4),
        C6       VARCHAR(15));
  
  Step TWO. Populate Table TBL1 with four rows.
  
    INSERT INTO TBL1 VALUES (1, NULL, 3, NULL, 'A1', 'AA');
    INSERT INTO TBL1 VALUES (2, 100, 2, NULL, 'A2', 'AA');
    INSERT INTO TBL1 VALUES (3, 100, 1, 100, 'A3', 'AA');
    INSERT INTO TBL1 VALUES (4, 100, 0, 100, 'A4', 'AA');
  
  Step THREE. Perform the following query with a CASE
  statement.
  
    SELECT C5, (CASE
       WHEN C1 = 5 THEN 'FIVE'
       WHEN C4 IS NULL AND C5 = 'A2' THEN 'TWO'
       WHEN C4 IS NOT NULL AND C5 = 'A3' THEN 'THREE'
       WHEN C5 NOT IN ('A1', 'A2', 'A3') AND C1 = 4 THEN 'FOUR'
       WHEN C3 BETWEEN 2 AND 4 AND C5 = 'A1' THEN 'ONE'
        ELSE 'NONE'
       END)
  FROM TBL1;
  
  So, for a large CASE statement, some 640+ elements could be
  easily result which could cause the incorrect branch
  instruction to be generated internally. However, please note
  that  200+ elements could easily occur if one of the elements
  is a decimal.
  
  In the above simple example, there are 12 elements in total.
  
  (1st WHEN = 1, 2nd WHEN = 2, 3rd WHEN = 2, 4th WHEN = 4,
  and 5th WHEN = 3),  1 + 2 + 2 + 4 + 3 is 12.
  

Problem conclusion

• Db2 has been modified to correct the logic to generate the
  proper branch instruction for a large CASE statement (as
  illustrated).
  
  Additional Keywords: SQLCASE SQLIN SQLNOTIN SQLISNULL
                       SQLISNOTNULL SQLBETWEEN
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UI58388

Modules/Macros

• DSNXGCAS
  

Fix information

• Fixed component name

  DB2 OS/390 & Z/

• Fixed component ID

  5740XYR00

Applicable component levels

• RC10 PSY UI58388

     UP18/09/25 P F809

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.