#### 2.6.1 Environment Variables for the Microcode

These environment variables are referred to by the microcode (the executable C program called `mit-scheme` under unix, and `mit-scheme.exe` on the PC).

`MITSCHEME_BAND`

  The initial band to be loaded. The default value is `all.com`.

`MITSCHEME_LIBRARY_PATH`

  A list of directories. These directories are searched, left to right, to find bands and various other files. On unix systems the list is colon-separated, with the default `/usr/local/lib/mit-scheme-ARCH`. On PC systems the list is semicolon-separated with the default `c:\local\mit-scheme`.

`MITSCHEME_CONSTANT`

  The size of constant space, in 1024-word blocks; overridden by `--constant`. The default value is computed to be the correct size for the band being loaded.

`MITSCHEME_HEAP_SIZE`

  The size of the heap, in 1024-word blocks; overridden by `--heap`. The default value depends on the architecture: for 32-bit machines the default is ‘`4096`’, and for 64-bit machines the default is ‘`16384`’.

`MITSCHEME_STACK_SIZE`

  The size of the stack, in 1024-word blocks; overridden by `--stack`. The default value is ‘`128`’.