# Changing &TEXMF; run-time parameters

You can control a number of run-time parameters (in particular, array sizes) on the command-line or in a configuration file.

Some of the more interesting paramaters:

main_memory

  Total words of memory available, for &TeX;, &METAFONT;, and &MetaPost;.

extra_mem_bot

  Extra space for large &TeX; data structures: boxes, glue, breakpoints, et al.

font_mem_size

  Words of font info available for &TeX;.

See , for a complete list of the &TEXMF; run-time parameters.

Here is a typical example of a configuration file:

    main_memory=2000000
    extra_mem_bot=2000000
    font_mem_size=2000000

The name of the configuration file is that of the engine (e.g., &miktexpdftex;) or format (e.g, &miktexpdflatex;). You use the `--edit-config-file` option of &initexmf; to edit the configuration file, e.g.:

    &prompt;initexmf --edit-config-file=pdflatex

    &prompt;

main_memory
extra_mem_bot
font_mem_size