SAP Buffer: Field description (FieldDescription)

What causes this issue?

The FieldDescription buffer (also called FTAB buffer) contains field
descriptions from the SAP R/3 Repository.
You can set the maximum size of the buffer using system parameter
<ZH>rsdb/ntab/ftabsize</>. The system sets the maximum number of
entries in the buffer directory depending on the maximum number of
entries in the TableDefinition buffer:
<ZH>2 * rsdb/ntab/entycount + 1</>
Specify the value for system parameter rsdb/ntab/ftabsize in kilobytes.

How to fix this error?

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

INCLUDE BC_BUFFER_INFO1 OBJECT DOKU ID TX LANGUAGE EN
A typical size setting for the buffer is around 20.000 - 30.000 KB.
INCLUDE BC_BUFFER_INFO2 OBJECT DOKU ID TX LANGUAGE EN

Error message extract from SAP system. Copyright SAP SE.