1. A method for processing a request from a sending computer that is a co-member of a message group of a sysplex coupled together using a signaling service, the method comprising: determining, by a receiving computer that is a co-member of the message group of the sysplex, that a signaling service message has been received from the sending computer that is a co-member of the message group of the sysplex, wherein the signaling service message relates to a data transfer between the sending computer and the receiving computer that are each a respective co-member of the message group of the sysplex; the message group of the sysplex comprises members defined to a cross-system coupling facility, wherein the cross-system coupling facility provides the signaling service; the signaling service message is received over a first communications channel defined by the signaling service; and the data transfer relates to an exchange of one or more files between the sending and receiving computers that are each a respective co-member of the message group of the sysplex using a second communications channel other than the first communications channel defined by the signaling service; decoding, by the receiving computer that is a co-member of the message group of the sysplex, the signaling service message to determine contents of the signaling service message related to the data transfer; and performing, by the receiving computer that is a co-member of the message group of the sysplex, an action related to the data transfer based on the contents of the signaling service message; wherein: the sending computer that is a co-member of the message group of the sysplex comprises a first data transfer module; and the receiving computer that is a co-member of the message group of the sysplex comprises a second data transfer module, wherein the data transfer modules communicate using the signaling service of the sysplex, wherein: the first data transfer module comprises a first control block data structure local to the sending computer that is a co-member of the message group of the sysplex; and the second data transfer module comprises a second control block data structure local to the receiving computer that is a co-member of the message group of the sysplex.