OSL

OSL is the IBM Corporation Optimization Subroutine Library, containing solvers for GAMS LP, and MIP model types. Note as of early 2004 IBM discontinued marketing of OSL.  OSL offers several algorithms for solving LP problems: a primal simplex method (the default), a dual simplex method, and three interior point methods: primal, primal-dual and primal-dual predictor-corrector.  For network problems there is a network solver.  The MIP solver is a branch and bound with cuts approach.  OSL can solve LP, MIP, and RMIP model types.  The solver manual is in OSL.pdf.  A variant for stochastic programs is also available in the form of OSLSE.  IBM discontinued development of OSL some time ago.

There are 2 alternative versions.

OSL3

OSLSE

OSL1 and OSL2 are older and now discontinued versions.