unrecognized configuration parameter "plpgsql.check_asserts"

Hi, hackers

Due to configure with parameter --enable-cassert, the debug_assertions is on by default, as follows:
postgres=# show debug_assertions;
debug_assertions
-------------------
on

Because of pgbench performance testing, I need to disable the assert function. Following the doc below, I tried to set plpgsql.check_asserts to off to disable assert function.
https://www.postgresql.org/docs/13/plpgsql-errors-and-messages.html

However, it prompts the following error, not sure if I missed something, any thoughts about it?
postgres=# alter system set plpgsql.check_asserts = off;
EORROR: unrecognized configuration parameter "plpgsql.check_asserts"

env:
PG: 13.2
OS: redhat 7.4 3.10.0-693.17.1.e17.x86_64
configure parameter: --enable-coverage --enable-tap-tests --enable-cassert --enable-debug --enable-nls --with-perl --with-python --with-tcl --with-openssl --with-ldap --with-libxml --with-libxslt --with-uuid=e2fs --with-segsize=10 --with-wal-blocksize=16 --with-llvm LLVM_CONFIG=xxx CLANG=xxx

thanks
walker