I don't think PellesC suite can create any .com file.
A .COM executable is a 16 bits executable preloaded at segmented address 0000:0100H. Means that the file itself can be put in memory starting from address 0000:0100H and run directly without any relocation.
PellesC is a 32/64bits compiler system that produce PE (for 32bits) and PE+ (for 64bits) executables suitable for flat linear addressing.
The PE, or PE+, format includes headers, sections and other structures used by the OS loader to load and, eventually, relocate code and data in memory.
The linker, POLINK, can't produce any segmented preloaded code.