You can optimise CALL statements in the following ways:
Use a literal in a CALL statement rather than a data-name, so that the statement can be optimized. For example:
CALL "myprog" USING
is faster than:
CALL program-name USING
where program-name is a data item containing the value myprog.
In unmanaged code, calling using a procedure pointer is efficient. However in .NET managed code, it is not.
Each CALL statement takes time, so try not to arbitrarily split a program into too many subprograms. On the other hand, small dynamically loadable programs make efficient use of memory, and may improve performance even though the calls themselves take time. In which case, use CALL and CANCEL to dynamically load the subprograms when they are needed. Note that cancelling a program does not, by default, free any memory.
CALL statements that do not alter the RETURN-CODE special register, or whose effect on RETURN-CODE are of no interest, should use a calling convention of 4. The Compiler directive DEFAULTCALLS can be used to set this globally.
Calls to the COBOL system library routines that carry out logical operations, such as CBL_AND, are optimized by the Compiler to actual machine logic operators, provided the parameters are eight bytes long or less and the length parameter is a literal value. These too should use a calling convention of 4.
Calls can be made faster by using call convention 256, which eliminates parameter-count checking on individual entry points.
