diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1087,7 +1087,7 @@ def resolverevlogstorevfsoptions(ui, req
     # experimental config: format.chunkcachesize
     chunkcachesize = ui.configint(b'format', b'chunkcachesize')
     if chunkcachesize is not None:
-        options[b'chunkcachesize'] = chunkcachesize
+        data_config.chunk_cache_size = chunkcachesize
 
     deltabothparents = ui.configbool(
         b'storage', b'revlog.optimize-delta-parent-choice'
diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -628,8 +628,6 @@ class revlog:
         else:
             new_header = REVLOG_DEFAULT_VERSION
 
-        if b'chunkcachesize' in opts:
-            self.data_config.chunk_cache_size = opts[b'chunkcachesize']
         if b'maxchainlen' in opts:
             self.delta_config.max_chain_len = opts[b'maxchainlen']
         if b'deltabothparents' in opts: