The following example uses the ALTER command to change the FREESPACE specification when loading a data set.

Assume that a large key-sequenced data set is to contain records with keys from 1 through 300␠000. It is expected to have no inserts in key range 1 through 100␠000, some inserts in key range 100␠001 through 200␠000, and heavy inserts in key range 200␠001 through 300␠000.

You can build this data structure as follows:

1. DEFINE CLUSTER and do one of the following:
   • Omit the FREESPACE parameter
   • Specify FREESPACE (0 0)
   • Specify DATACLAS and use the FREESPACE attribute assigned through the automatic class selection routines established by your storage administrator.
2. Load records 1 through 100␠000 with REPRO or any user program using a sequential insertion technique.
3. CLOSE the data set.
4. Change the FREESPACE value of the cluster with the access method services command ALTER clustername FREESPACE (0 5). Explicit specification of FREESPACE overrides the data class attribute assigned by your storage administrator.
5. Load records 100␠001 through 200␠000 with REPRO or any user program using a sequential insertion technique.
6. CLOSE the data set.
7. Change the FREESPACE value of the cluster with the access method services command ALTER clustername FREESPACE (5 20).
8. Load records 200␠001 through 300␠000 with REPRO or any user program using a sequential insertion technique.