Transactions to create pg_multixact members and offsets

Hellos,

How to manually increase pg_multixact members and offsets?

Does a transaction waiting for exclusive lock or shared lock result into entry being created in pg_multixact?

2  *

3  * multixact.c

4  * PostgreSQL multi-transaction-log manager

5  *

6  * The pg_multixact manager is a pg_clog-like manager that stores an array of

7  * MultiXactMember for each MultiXactId. It is a fundamental part of the

8  * shared-row-lock implementation.

Regards...