With the TOOLIN Interface, you supply ICETOOL statements in a data set defined by the TOOLIN DD statement. ICETOOL prints messages in the data set defined by the TOOLMSG DD statement.

With the Parameter List Interface, your program supplies ICETOOL statements in a parameter list. ICETOOL prints messages in the data set defined by the TOOLMSG DD statement and also puts information in the parameter list for use by your program.