Calling stored procedure dynamically from PB Script

Problem: Calling stored procedure dynamically from PB Script
 
Situation:
I have a Customer table. For each customer one stored procedure is assigned which is saved in a column in the Customer table.
When I am viewing a customer, then respective stored procedure has to be called. There are 1000 customers and each customer has his own stored procedure, so there are 1000 stored procedures.
Each of these stored procedures accept 3 string arguments and return one integer value.
 
 
Ex.
String ls_Cust_sp_name
 
ls_Cust_sp_name = 'sp_macdonalds_budget'     // This value is retrieved from the table for the selected customer
 
// Standard way of calling a stored procedure, where the stored proc actual name is called,
// DECLARE lsp_validate_sp PROCEDURE FOR sp_macdonalds_budget(:ls_Budget_ID, :ls_Status_ID, :ls_Resp_Person );  // Here stored proc name is hardcode, hence does not server my purpose and it is not optimized.
// EXECUTE lsp_validate_sp;
 
 
DECLARE lsp_validate_sp PROCEDURE FOR ls_Cust_sp_name(:ls_Budget_ID, :ls_Status_ID, :ls_Resp_Person );    // I get compilation error, stating 'ls_Cust_sp_name' procedure not found.
EXECUTE lsp_validate_sp;

FETCH lsp_validate_sp INTO :li_Retn_Val;
 
How can I call the stored procedure in an optimized way without using CHOOSE... Case or any other loops. There can be more than 1000 customers and stored procedures.