1. A computer-implemented method of clearing blocks of storage class memory in a computing environment comprising main storage and storage class memory, said computer-implemented method comprising: obtaining, by a processor, an operation block from main storage, the operation block including an indication of a move specification block (MSB), the move specification block being configured to include an operation code field, a block count field, a storage class memory address field for addressing storage class memory, a block size field and a flags field; obtaining, by the processor, the move specification block; based on a flag of the flags field of the obtained move specification block having a first value, performing: based on an operation code in the operation code field of the obtained move specification block, determining that the obtained move specification block is configured to clear blocks of storage class memory; determining a size of the block of storage class memory to be cleared and a number of blocks to be cleared based on the block size field and the block count field of the obtained move specification block; and based on the determining, clearing the blocks of storage class memory associated with a storage class memory address of the storage class memory address field of the obtained move specification block.