SAP system procedures are stored in the database sybsystemprocs.
When a user in any database executes a system stored procedure (that is, a procedure that has a name beginning with sp_), SAP ASE first looks for that procedure in the user’s current database. If there is no procedure there with that name, SAP ASE looks for it in sybsystemprocs. If there is no procedure in sybsystemprocs, SAP ASE looks for the procedure in master.
If the procedure modifies system tables (for example, sp_adduser modifies the sysusers table), the changes are made in the database from which the procedure was executed.
To change the default permissions on system procedures, modify those permissions in sybsystemprocs.