I want to know that how much plagiarism is allowed for the acceptance of a research paper in ACM, IEEE, Elsevier, Springer and any other referred Journals?
Exactly as stated by Michael. Plagiarism has two components. Referring to the work by somebody else and giving them the credit. That is OK. Second is copying somebody's work and trying to pass it off as your own. This is totally unacceptable. Overall, my assessment is at-least 60% of any work should be original.