How can I compare the DSN for a specific high level qualifier, or other character field for just the first couple of characters?
CA 1 12.6 and 14.0
Define the high level qualifier as a character field in the CONTROL-SECTION.
Example: DEFINE MYDSN CH 'SYS1'
In the PROCESS-SECTION of your code use the WHEN statement with your field as the first operand. The first operand determines the length of the compare.
Example: WHEN MYDSN EQ DSN