Logical logs *newbie* question

We are running IDS 7.3. When I do an onstat -d there's only 206 free pages available from a total of 75259. Here's what I don't understand. I do an entire backup ontape -s 0 over the weekend when there's nobody using the system. After the backup the free pages remains the same. If there's no transactions going on and the backup has flagged the logs as being backed up, why does the free pages not get larger? Thanks Gary Quiring onstat -d output: Informix Dynamic Server Version 7.30.UC2 -- On-Line -- Up 4 days 23:17:22 -- 323584 Kbytes Dbspaces address number flags fchunk nchunks flags owner name 8fc4613c 1 1 1 1 N informix rootdbs 8fc47198 2 1 2 1 N informix data1dbs 8fc47254 3 1 3 3 N informix data2dbs 8fc47310 5 1 5 1 N informix data4dbs 8fc473cc 7 2001 7 1 N T informix tempdbs 8fc47488 8 1 8 1 N informix logdbs 6 active, 2047 maximum Chunks address chk/dbs offset size free bpages flags pathname 8fc461f8 1 1 0 100000 73515 PO- /dev/rrootdbs 8fc46b94 2 2 0 1024000 1023947 PO- /dev/rdata1dbs 8fc46c70 3 3 0 1024000 9007 PO- /dev/rdata2dbs 8fc46d4c 4 3 0 997997 600938 PO- /dev/rdata3dbs 8fc46e28 5 5 0 1024000 785866 PO- /dev/rdata4dbs 8fc46f04 6 3 0 1024000 1023997 PO- /dev/rdata5dbs 8fc46fe0 7 7 0 1024000 1022577 PO- /dev/rtempdbs 8fc470bc 8 8 0 75259 206 PO- /dev/rlogdbs 8 active, 2047 maximum