As the message says you can try issuing the commands
DIREct,SPARse
followed by
TANGent,,1
This will use a sparse storage scheme. This will save you a little memory but may not be enough. In which case, you should
try using ITERative instead of DIREct,SPARse; for example
ITERative,PCG
TANGent,,1
See the manual for other preconditioning options.