Official mbed Real Time Operating System based on the RTX implementation of the CMSIS-RTOS API open standard.
I found mbed-rtos hangs at start up with NUCLEO-L476RG. The program is the combination with latest mbed-rtos and as is Nucleo_rtos_basic example. Increase of stack size does not affect. If I tested with NUCLEO-L053RG and NUCLEO-F401RG, there was no problem. My short examination find that it work if it with revision till 111. But after rev 112, it makes hang. I make diff between 111 and 112, but cannot find L476RG specific change. I cannot tell this is L476RG side matter or mbed-rtos matter. Hopes improvement.