ISPTLIB is the Table Input Library and is required.
ISPTABL is the Table Output Library and is optional. You must allocate it only if an application uses table services.
The table output library must be a partitioned data set. The ISPTABL ddname that defines the table output library can specify the same data set as the table input library, ddname ISPTLIB. The first data set in the ISPTLIB concatenation should be the same as the data set used for ISPTABL. This ensures predictable behavior of dialogs that use table services without specifying the LIBRARY keyword. The output and input data sets must be the same if the updated version of a table is to be reprocessed by the same dialog that updated it.
You must allocate the table output library to ddname ISPTABL before using table services.