S0C6 specification exception

S0C6 is a specification exception: an operand violates hardware rules, such as a misaligned address or an invalid packed-decimal length.

What it means

• The instruction itself is valid, but one of its operands breaks a hardware rule.
• Common in COBOL when packed-decimal fields have odd definitions or pointers are misaligned.

Common causes

• Packed-decimal field defined with an even number of digits used in arithmetic.
• Misaligned binary (COMP) field from a bad REDEFINES.
• Invalid length on a variable-length operand.

How to diagnose

• Map the failing offset to the statement; inspect the field definitions involved.
• Display the fields in hex and check digit counts and alignment.

How to fix it

• Correct the PIC clause so packed fields have valid lengths.
• Fix the REDEFINES so COMP fields start on proper boundaries.

Example: Valid packed-decimal definition

Odd digit counts keep packed-decimal operations valid.

Interview tip

• Q: How would you troubleshoot a S0C6 specification exception in production?
• A: I would map the failing statement, check the PIC clauses and alignment of every operand, and correct the definition.

Prevention checklist

• Review PIC clauses for packed fields.
• Test boundary values.