Rules for defining parameters and attributes

These rules apply to the callable services:

Parameters are required and positional.
Each parameter list has a fixed number of parameters.
Each parameter is defined as an integer or a character string. Null pointers are not acceptable for any parameter.
Keywords that are passed to the callable services, such as CLEAR, CBC, and FIRST can be in lowercase, uppercase, or mixed case. The callable services fold them to uppercase prior to using them.

Each callable service defines its own list of parameters. The entire list must be supplied on every call. If you do not use a specific parameter, you must supply that parameter with hexadecimal zeros or binary zeros.

Parameters are passed to the callable service. All information that is exchanged between the application program and the callable service is through parameters that are passed on the call.

Each parameter definition begins with the direction that the data flows and the attributes that the parameter must possess (called “type”). This describes the direction.

Direction: Meaning
Input: The application sends (supplies) the parameter to the callable service. The callable service does not change the value of the parameter.
Output: The callable service returns the parameter to the application program. The callable service may have changed the value of the parameter on return.
Input/Output: The application sends (supplies) the parameter to the callable service. The callable service may have changed the value of the parameter on return.

This describes the attributes or type.

Type: Meaning
Integer (I): A 4-byte (32-bit), twos complement, binary number that has sign significance.
String: A series of bytes where the sequence of the bytes must be maintained. Each byte can take on any bit configuration. The string consists only of data bytes. No string terminators, field-length values, or type-casting parameters are included. The maximum size of a string is X'7FFFFFFF' or 2 gigabytes. In some of the callable services, the length of some string data has an upper bound defined by the installation. The upper bound of a string can also be defined by the service.
Alphanumeric character string: A string of bytes in which each byte represents characters from this set:

           EBCDIC                EBCDIC                EBCDIC
Character  Value      Character  Value      Character  Value

A-Z                   (          X'4D'      /           X'61'
a-z                   )          X'5D'      ,           X'6B'
0-9                   +          X'4E'      %           X'6C'
Blank      X'40'      &          X'50'      ?           X'6F'
*          X'5C'      .          X'4B'      :           X'7A'
<          X'4C'      ;          X'5E'      =           X'7E'
>          X'6E'      -          X'60'      '           X'7D'