People sometimes get messages saying `memory capacity exceeded'.
Most of the time this error can be fixed
without enlarging TeX. The most common causes are unmatched braces,
extra-long lines, and poorly-written macros. Extra-long lines are
often introduced when files are transferred incorrectly between
operating systems, and line-endings are not preserved properly (the
tell-tale sign of an extra-long line error is the complaint
that the `buf_size' has overflowed).
If you really need to extend your TeX's capacity, the proper method depends on your installation. In the purest form, you change the parameters in module 11 of the WEB source. In less pure forms, you might need to modify a change file, or perhaps change some environment variables; emTeX allows you to adjust the memory allocation criteria on the command line. Consult the documentation that came with your implementation.