The preferred way to control the behavior of the STPBEGIN/STPEND macros is by use of input parameters, not by hard coding values with a %LET statement.
For example, if you want to control the ODS style that is used, register a parameter named _ODSSTYLE and give it a default value. At run-time, users will be able to specify the value they want to use. If you don't want the user to change the value at run-time, clear the "Modifiable" and "Visible" check boxes for this parameter.
A list of parameter names can be found at:
http://support.sas.com/rnd/itech/doc9/dev_guide/stprocess/reserved.html
Parameters that are specific to the STPBEGIN/STPEND macros will have "%STPBEGIN/%STPEND" in the "Used by" column.
Vince DelGobbo
SAS R&D