I'm using umfpack for solving large systems of equation. However, I'm constantly getting out of memory issues for even modest size problems as pre2, torso3, ohne2 Hamrle3 (all from Tim Devis's collection). The useable memory is 44GB in machine where I'm trying to run.
These problems are not too big that index would be out of 2GB (I'm using 32 bit integers). One way would be try out 64 bit integer version. However, I might be making a mistake in choosing the parameters itself for the symbolic factorization, which right now is all set to default.