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(web2c.info)Runtime options

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Runtime options
===============

  Besides the configure- and compile-time options described in the
previous sections, you can control a number of parameters (in
particular, array sizes) in the `texmf.cnf' runtime file read by
Kpathsea (Note: Config files.).

  Rather than exhaustively listing them here, please see the last
section of the distributed `kpathsea/texmf.cnf'.  Some of the more
interesting values:

`main_memory'
     Total words of memory available, for TeX, Metafont, and MetaPost.
     Must remake the format file after changing.

`extra_mem_bot'
     Extra space for "large" TeX data structures: boxes, glue,
     breakpoints, et al.  If you use PiCTeX, you may well want to set
     this.

`font_mem_size'
     Words of font info available for TeX; this is approximately the
     total size of all TFM files read.

`hash_extra'
     Additional space for the hash table of control sequence names.
     Approximately 10,000 control sequences can be stored in the main
     hash table; if you have a large book with numerous
     cross-references, this might not be enough, and thus you will want
     to set `hash_extra'.

  Of course, ideally all arrays would be dynamically expanded as
necessary, so the only limiting factor would be the amount of swap space
available.  Unfortunately, implementing this is extremely difficult, as
the fixed size of arrays is assumed in many places throughout the source
code.  These runtime limits are a practical compromise between the
compile-time limits in previous versions, and truly dynamic arrays.  (On
the other hand, the Web2c BibTeX implementation does do dynamic
reallocation of some arrays.)