TCMAPKMAXSIZ is used in assignments & comparisons both as bitmask and as integer.

[eulores]

In file tcutil.c the constant TCMAPKMAXSIZ is defined as:
#define TCMAPKMAXSIZ 0xfffff

Further down in the file, some excerpts make use of the constant:

a) ... = rec->ksiz & TCMAPKMAXSIZ
b) if(ksiz > TCMAPKMAXSIZ) ...
c) hash &= ~TCMAPKMAXSIZ

If someone changes the #define to a number not consisting of a sequence of binary "1", then statements a) and c) will fail.

I suggest rewriting the #define to something like:
# define TCMAPKMAXSIZ ((1 << 20) - 1)

Otherwise, rewriting statements a) and c) by using for example the ternary operator (?:).