Running out of code compiler limit while using Keil is headache. GCC solve this problem (Least mine!).
This procedure is partially copied from ExploreEmbedded wiki page.
That explain "Using ARM GCC with LPC1768" Here is the link- https://exploreembedded.com/wiki/Using_ARM_GCC_with_LPC_1768
This templete is only able to compile code for LPC2148.