DD statement DISP parameter for GSAM data sets

The DD statement DISP parameter varies, depending on whether you are creating input or output data sets and how you plan to use the data sets.

Attention: Specifying the DISP=OLD or DISP=SHR parameter for a normal start with non-empty data sets will overwrite the existing records from the beginning of the data set.
  • For input data sets, use the DISP=OLD parameter.
  • For output data sets, consider the following options:
    • To create an output data set allocated by the DD statement, set DISP=NEW.
    • To add new records to an empty data set when performing normal start or a restart after failure, set DISP=MOD, DISP=SHR, or DISP=OLD.
    • When restarting the step, set DISP=OLD for existing data sets and DISP=MOD for empty data sets.
    • To add new records to an existing non-empty data set when performing a restart after failure, set DISP=MOD, DISP=SHR, or DISP=OLD. These parameters add new records from the restart point on the existing data set.
    • To add new records to the end of an existing non-empty data set when performing normal start, set DISP=MOD.