Is the parameter local_mem_size in the FPGA a quantity that can be modified? How do I get it if I need a larger local_mem?
Just like every other hardware, there is a limit on the amount of Block RAM and registers on a given FPGA, using which OpenCL "Local Memory" is implemented. If your code uses less than the amount that is available on the chip, everything will be fine. If it uses more, your kernel will not fit on the device and compilation will fail.