Small comment to previous response... The table is indeed CEPC_BUKRS. The logic is that if PCtr is assigned to all company codes within the relevant controlling area, then it won't appear in this table. Only PCtrs which are assigned to a part of company codes will appear.
After you make company code assignment changes to a PC, but BEFORE you activate the PC, the data appears in table CMDT_PC_BUKRS .
Once you activate the PC after making your changes, the data resides in table CEPC_BUKRS .
Trust this helps.