Subprograms › Linkage Conventions for Non-Ideal Subprograms › Parameter Rules

Parameter Rules

The following rules apply when a CA Ideal program calls a non-Ideal subprogram:

• The name of the called program must be in the resource table of the calling program and must conform to CA Ideal naming conventions, with the additional restriction that the name cannot contain hyphens (due to operating system requirements).
• You must specify a parameter in the subprogram for each data item to pass. The parameter definitions must match the type of each data item.

  You can pass a maximum of 16 data items from a CA Ideal program to a non-Ideal subprogram.

  A compile-time error occurs if a CALL statement attempts to pass more data items than the number of level-1 parameters defined for the subprogram.

  Unpredictable results occur when a subprogram references a parameter that corresponds to a data item that was not passed.

• The following restrictions apply to specific attributes:
  • alphanumeric-The corresponding parameter must be alphanumeric. When the program is called, a MOVE BY POSITION is performed. When the length of the data item is not the same as the parameter, the data is padded or truncated as required to fit.
  • numeric-The corresponding parameter must be defined as a packed decimal, zoned decimal, or binary. When the program is called, a MOVE BY POSITION is performed. The data item can be converted and decimal aligned.
  • date-Same as numeric.
  • flag-Not allowed.
  • group name-The structures must be compatible using the tests for the MOVE BY POSITION command.
  • condition name-Not allowed.
  • redefines-Ignored.
• The parameter definitions of a non-Ideal subprogram actually become part of the calling program. Therefore, you must define parameter data for the non-Ideal subprogram before the calling program is compiled. The calling program must be recompiled if the subprogram's parameter data changes.
• The parameters for non-Ideal programs are linked as follows:
  • In batch (z/OS and VSE), standard linkage is used (R1 points to a parameter list)
  • In CICS (z/OS and VSE), the address list for the parameters is stored in the beginning of the TWA (Transaction Work Area).
• The designation of the parameters on the CALL statement should match the parameter definition. When the designation of a data item as UPDATE or INPUT in the CALL statement does not match the parameter definition of U or I for the called program, the following applies:
  • If the parameter is defined as I-input and sent as U-update on the CALL statement, an error does not occur as long as the called program only references the parameter. If the non-Ideal subprogram attempts to update the parameter, the passed data item is not updated.
  • If the parameter is defined as U-update and sent as I-input, a compile error occurs regardless of whether the subprogram attempts to modify the data item.