What are the assembler DC/DS operands, and how do I use them?
HLASM provides assembler directives for defining variables and constants
Assembler programs reference storage areas during program execution. The storage areas may be defined within the scope of the application program code or be located elsewhere in memory. High Level Assembler (HLASM) provides two assembler directives which an assembler application programmer uses to define these storage areas: DC (Define Constant) and DS (Define Storage). The key difference being DC will initialize the storage area, DS will not.
The attached pdf explains some of the details of these two instructions and shows examples of using them.