Regarding pg_multixact/members folder size cleanup in postgres 9.3.6.

Dear All,

Thanks for your support and guidance.
I am using postgres 9.3.6 version and i am using multiple INSERT/UPDATE SQL
commands with explicit share lock.
I know pg_multixact/members folder contains transactions of share lock.

But these files are continuously increases.
I have checked PostgreSQL conf file and by default parameters are used in
my system.
When i have checked same behaviour in older versions of PostgreSQL, this
folder size was not increased and continuously cleanup in older versions.
Some one please let me know below points. It will really helpful to
understand postgres behavior.
1. When this folder pg_multixact/members folder size will cleanup?
2. How can i identify that at that time it will start cleanup?
3. Does it depends on some postgres config parameters? What is config
parameters and what will be value of that parameter?
4. I Want older postgres behavior in newer versions. So how to set this
behavior through postgres parameters?

Thanks in advance.

Regards,
Yogesh