Null Parameter Values

Use two commas (,,) to give a parameter variable a null value when it is followed by other non-null parameters. After the last non-null parameter, all remaining parameter variables up to &31 are automatically given null values. Null parameters are useful when a value is not required. For example, assume that you wrote a command list called CONN that contained the following statement:

BGNSESS FLSCN,APPLID=&1,SRCLU=&2,LOGMODE=&3,INT=&4,D=&5

If you do not want to specify all the values, you can enter the following command:

CONN TSO,TAF01F00,,,PF12

In this example, &1 is TSO, &2 is TAF01F00, &3 and &4 are null, and &5 is PF12. The extra commas between TAF01F00 and PF12 represent positional place holders for &3 and &4, and tells the command list that they are null. If you use only one comma, the command list takes PF12 as &3 and incorrectly uses PF12 as the LOGMODE.

Test for null parameter variables in your command list and provide default values to avoid possible syntax errors.