There's a phrase, "truth in advertising." That's what we've got here. The title informs us that we're about to get 112 lines of anger and pain. It suggests sheer, animalistic emotion, like a wolf howling at the moon. Rather than making tightly controlled, logical arguments, the speaker is going to release all the pent-up emotion inside of him, consequences be damned.
The word "howl" appears only once in the poem, in the past tense, in line 35: "who howled on their knees in the subway and were dragged off the roof waving genitals and manuscripts."
The working title of Howl was "Strophes," from the Greek word for poetic verses (Source). If he kept this title, it would have been like naming a poem, "Poem." Interesting, but we're glad he settled on something different.
The dedication "for Carl Solomon" is also part of the full title: Howl for Carl Solomon. For the reader then, it helps to know something about Solomon's relationship to Ginsberg and his mental illness (see "In a Nutshell"). More than just a dedication, the full title tells us that the poem was written on someone else's behalf. The poem is not just about venting frustration, it's about venting frustration to support a friend.