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Pointers

Some structures need to address optional data that might be discontiguous with the structure, such as the MQOR and MQRR records addressed by the MQOD structure. To address this optional data, the structures contain fields that are declared with the pointer data type. However, COBOL does not support the pointer data type in all environments. Because of this, the optional data can also be addressed using fields that contain the offset of the data from the start of the structure.

If you want to port an application between environments, ascertain whether the pointer data type is available in all the intended environments. If it is not, the application must address the optional data using the offset fields instead of the pointer fields.

In those environments where pointers are not supported, declare the pointer fields as byte strings of the appropriate length, with the initial value being the all-null byte string. Do not alter this initial value if you are using the offset fields.

 

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