"enable indexes" & /tmp on UW2.1

In order to force Informix (7.2 on UnixWare 2.1) to recreate the indexes from time to time, a script run weekly disables, then re-enables the indexes in all tables of my database, one table at a time. This script runs fine, but now we get error messages from the OS, saying that all /tmp space is used during this operation. Some tracing revealed that this happens during the "alter table ... enable indexes" for the biggest table. This table has some 3M rows, of 61 bytes per row. The /tmp space is 50MB. It is all used (from being nearly empty at the start of the operation). Has anyone some explanation for this ? How can I avoid this (because filling /tmp completely is not really ideal for a Unix kernel ...) Frank Clarijs, Unisys Belgium