A Workbook consists of a number of worksheets. Each worksheet consists of
256 columns and 65,536 rows (These are not maximums or minimums as that
would imply they can be changed - You have 256C*65536R period). These
cannot be changed. If your data needs more than 256 columns, such as you
have indicated then you would need to split your data manually across about
4 worksheets. Depending on what your data is, and the needs you have wrt
working with it and what data you want to extract from it, this may or may
not be suitable. Give us some idea of how many rows of data you have that
will take 1000 columns, what kind of data it is, and what sort of things you
need to be able to do with it, eg what kind of reports etc.