Uninitialized storage (1)

Assumptions about the state of uninitialized storage can bite the best of us. Last year we ran into a problem with the Cobol code generated by the SQL Coprocessor using Enterprise Cobol 3.3 under DB2 V8.

In the SQL---PLIST it was generating the following FILLER area:

02 SQL---STMT-NUM PIC S9(9) COMP-5.
02 FILLER PIC X(20).

Apparently the FILLER area is used by DB2 to store some bit switches and its logic assumes that initially the FILLER contains x'00'. *Usually* this is true, but we ran into some very weird application abends in a production IMS MPR.

It turned out that we were a bit behind in our Cobol maintenance. After the maintenance was applied the generated code changed to:

02 SQL---STMT-NUM PIC S9(9) COMP-5.
02 FILLER PIC X(20) VALUE IS
X'0000000000000000000000000000000000000000.

In my experience this is one of the very few times which a programmer's protest that "It's not my fault!" turned out to be true.