Packed data sets

The packed data set format allows you to use direct access storage devices (DASD) more efficiently. In this format, ISPF replaces any repeating characters with a sequence showing how many times the character is repeated. Before you can properly use data stored in this format as input to processing programs, such as compilers, you must first tell ISPF to unpack and expand the data.

The two requirements for using packed data sets are:

To store data in packed format:
- Enter the PACK ON Edit primary command while editing a data set or PDS member.
- Select the Pack Option field (under To Data Set Options:) when copying or moving members using the Move/Copy utility (option 3.3).
To unpack and expand packed data for processing, select the Source Data Packed field on the Foreground Selection panel or the Batch Selection panel. You must select this field if any of the input data, including that referred to in COPY or INCLUDE statements, is in packed format.