monitor RAM usage

Most embedded code uses static allocation, as it's apt not to fail due to fragmentation and leakage. For that you'd look at your .MAP file.

in the .map file, at ''Memory Map of the image'' section, the Size in ''Execution Region RW_IRAM1'', would this be the RAM usage?

Assuming Keil, but you should really be specific about what you use, because I don't know

Execution Region RW_IRAM1 (Base: 0x20000000, Size: 0x00003550, Max: 0x00018000, ABSOLUTE, COMPRESSED[0x00000278])
Base Addr Size Type Attr Idx E Section Name Object
0x20000000 0x000004f4 Data RW 237 .data main.o
0x200004f4 0x00000004 Data RW 238 .data main.o
0x200004f8 0x00000004 Data RW 239 .data main.o
0x200004fc 0x00000004 Data RW 247 .data main.o
0x20000500 0x00000004 Data RW 249 .data main.o
0x20000504 0x00000010 Data RW 3774 .data stm32f2xx_rcc.o
0x20000514 0x00000004 Data RW 5999 .data mc_w.l(errno.o)
0x20000518 0x00002038 Zero RW 231 .bss main.o
0x20002550 0x00001000 Zero RW 5562 STACK startup_stm32f2xx.o
..
Total RW Size (RW Data + ZI Data) 13648 ( 33kB)