Calc/hacks/number of rows
Regard this article as historical, though the content is still applicable to columns or in case you want to increase the number of rows to 2097152 (2M ;-)
Now and then people ask whether increasing the row limit above 64k lines or the column limit above 256 columns for OpenOffice.org version 2.4 or 1024 columns for 3.0 would be possible.
Well, it depends on your goal. For personal use, you may set
MAXROWCOUNT_DEFINE in sc/inc/address.hxx to
a different value, multiple of 128, then recompile the application respectively the libsc680*.so and shove it under your existing installation. However, doing so implies that you don't save to any binary file format like Excel or whatsoever, otherwise you risk loss of data. You'll also encounter drawing layer misfits in higher row numbers, may experience performance problems, and there maybe other quirks. It generally works for data and formulas, but otherwise is completely untested.
For the number of columns, the same applies to the
MAXCOLCOUNT_DEFINE in sc/inc/address.hxx, except that the value must be a multiple of 16 instead.
A successful proof of concept was done by Laurent Godard, using 2,000,000 rows and 32,000 columns, resulting in the lower right corner cell address AUHT2000000 ... see http://blogs.nuxeo.com/dev/2006/08/the-spreadsheet-next.html
Please note again that this is a hack. Although it may serve you for some data crunching, exchanging documents with other releases or applications will not work.
However, we should implement this expansion properly, also to be able to handle larger spreadsheet documents created with other applications. There are RFEs for this, http://qa.openoffice.org/issues/show_bug.cgi?id=30215 for number of rows and http://qa.openoffice.org/issues/show_bug.cgi?id=86049 for number of columns.