Causes the Collector to use the default performance data file
    name. The default data file name consists of the name of the user
    program's executable image and the .PCA file type. You get the
    default file name if you do not use the SET DATAFILE command.
    However, you need the /EXECUTABLE qualifier if you want the
    default file name and you also want to specify the /APPEND or
    /SHAREABLE qualifier. If you specify the /EXECUTABLE qualifier,
    omit the file-spec parameter.