Maximum on HTTP header values?

Is there an accepted maximum allowed size for HTTP headers? If so, what is it? If not, is this something that's server specific or is the accepted standard to allow headers of any size?

[yyamano]

“ the HTTP spec does not define a limit, however many servers do by default. This means, practically speaking, the lower limit is 8K.”

[authorNari]

HTTPヘッダのサイズ制限について、nginxは4K-8K、トータルで

[shimooka]

ヘッダの最大長について。最大長だけでなく、フィールド数やヘッダ行数、ボディ長も変更できるらしい。