Release of space in a table

I am using informix 7.31. I have deleted rows from a big table and I need to claim the space back that it was holding. What command can I use without unloading and reloading the table.

alter anindex_from_that_table to cluster, alter fragment on table <yourtable> init in ..... warning if the remaining table is huge then be aware of long trx rollbacks Superboer.