carta
libressl-SSL_CTX_sess_set_cache_size(3)

libressl-SSL_CTX_sess_set_cache_size3

Manipulate session cache size

Usage

SSL Library (libssl, -lssl) libcrypto

long

long

Overview

SSL_CTX_sess_set_cache_size() sets the size of the internal session cache of context ctx to t.

SSL_CTX_sess_get_cache_size() returns the currently valid session cache size.

The internal session cache size is SSL_SESSION_CACHE_MAX_SIZE_DEFAULT, currently 1024×20, so that up to 20000 sessions can be held. This size can be modified using the SSL_CTX_sess_set_cache_size() call. A special case is the size 0, which is used for unlimited size.

If adding the session makes the cache exceed its size, then unused sessions are dropped from the end of the cache. Cache space may also be reclaimed by calling SSL_CTX_flush_sessions(3) to remove expired sessions.

If the size of the session cache is reduced and more sessions are already in the session cache, old session will be removed the next time a session shall be added. This removal is not synchronized with the expiration of sessions.

Return values

SSL_CTX_sess_set_cache_size() returns the previously valid size.

SSL_CTX_sess_get_cache_size() returns the currently valid size.

History

SSL_CTX_sess_set_cache_size() and SSL_CTX_sess_get_cache_size() first appeared in SSLeay 0.9.0 and have been available since OpenBSD 2.4.

From libressl 4.4.0-1 in Arch Linux 2026-11-01. Parsed by carta from the page's mdoc source.