How in PostgreSQL to adjust the size of the cached amount of data for selects?

Question

PostgreSQL

Hello.
Please help me figure it out (PostgreSQL 10, xubuntu, x86):
Is there a configuration parameter in PostgreSQL that can be changed to control the amount of data that remains in the cache after fetching from a table?

Situation:
Step1: I do a select from the table, explain analyze shows that the data is read from the disk (shared read);
Step2: again I do the same select from the same table, explain analyze shows that 32 pages (blocks) were read from the cache (shared hit), the rest from disk;
Step3: the same select, 64 pages are read from the cache, the rest is from disk.
And so on, at each step +32 pages get into the buffer.

How can I influence this size? For example, set to cache 320 pages?
(I searched in Google, I did not find the answer)

In the picture below, you can visually see: